When did Qin Shihuang reuse Lisi, after or before the reunification of the country, we should have evidence.

Before Qin Shihuang unified China. Politicians of the Qin Dynasty. At the end of the Warring States Period, a native of Shangcai (now southwest of Shangcai, Henan Province) was born in Chu. In his early years, he was a small official in the county. Later, he came to Xunzi to learn the art of emperors and entered the Qin Dynasty. At first, he was regarded as Lang, and then he persuaded the King of Qin to destroy the princes and proclaimed himself emperor, and was appointed as a long history. The king of Qin adopted his strategy and sent advisers to lobby the six countries of Kanto with gold and jade, alienating the princes and ministers of various countries and making them guests and ministers. In the tenth year of the King of Qin (237 BC), he ordered the expulsion of six guest ministers. Li Si's "Persuade to Expel" stopped it, which was adopted by the Qin government, and soon the official arrived at Ting Wei. It played a great role in the cause of unifying the six countries in the Qin Dynasty. After Qin unified the world, he agreed with Wang Wan and Feng Jie to respect Qin as emperor, and formulated relevant etiquette systems. Be appointed as prime minister. He suggested tearing down the county wall, destroying folk weapons and strengthening the rule of the people; Oppose the enfeoffment system and adhere to the county system; He also advocated burning poems, books and hundreds of languages collected by the people, and forbidding private learning in order to strengthen autocratic and centralized rule. He also participated in the formulation of laws to unify the system of tracks, characters and weights and measures. After the death of Qin Shihuang, he conspired with Zhao Gao to forge a will, forcing Fu Su, the eldest son of the first emperor, to commit suicide, and made Hu Hai, the youngest son, the second emperor. Later, Zhao Gao was jealous. In the second year of Qin Ershi (the first 208 years), he was beheaded in Xianyang City, and the three clans were conquered. Reese's philosophy of life is "mouse philosophy". Man is a mouse, and he is also a mouse, but it can be divided into granary mouse and street mouse. I want to be a mouse in the granary. For this goal, Reese has struggled all his life. When he died, he sighed, "The taller the hamster, the farther it fell." Reese worked as a poor boy when he was young, and later worshipped Xunzi as a teacher, learning the art of emperors and the way of governing the country. After finishing his studies, he analyzed the situation at that time and thought that "Chu is weak and all six countries are weak". Only Qin had the conditions to unify the world and establish imperial industry, so he decided to go to Qin to display his talents and ambitions. In 247 BC, Lisi came to the State of Qin and worked as a public guest for the first time under Lv Buwei, the prime minister of the State of Qin. After gaining Lu's trust, Li Si became the personal footman of the King of Qin (Qin Shihuang Ying Zheng). Reese took advantage of his frequent approach to the king of Qin to give him a book on reunification, and persuaded him to seize the opportunity of "eternal beauty" to "destroy the king as the emperor" and realize "unification of the world". Wang Zheng of the State of Qin readily accepted Lisi's suggestion, first appointed him as a long history, then worshipped him as a guest minister, and ordered him to formulate strategies and arrangements for annexing the six countries and unifying the world. In 237 BC, under the pretext of Zheng Guo, a Korean water conservancy engineer, the nobles of the imperial clan of Qin engaged in espionage activities in Qin, that is, they used the water conservancy project (Zheng Guoqu) to weaken the national strength of Qin, and asked the king of Qin to order the expulsion of six ministers, and Reese was also deported. On the way out of Qin, Reese wrote an exhortation and expulsion letter, urging the king of Qin to take back his life. In "Zhuke Shu", he listed a large number of historical facts, expounded Ke Qingshi's contribution to Qin, and urged to recruit talents regardless of country or region in order to realize the great cause of reunification. The book of remonstration and expulsion deeply touched the king of Qin. He immediately canceled the expulsion order, restored Reese's official position, and soon promoted him to Ting Wei. The book of remonstrating and expelling guests is not only a precious historical document, but also a well-known masterpiece. Mr. Lu Xun once said: "In the article of Qin Dynasty, Li Si is only one person." After being used seriously, Li Si, with his outstanding political talent and foresight, followed the trend of historical development, helped Zheng formulate a strategic plan to annex the six countries and realize reunification, and worked hard to organize and implement it. As a result, it took only ten years to destroy the six countries, and in 22 1 BC, the first unified and centralized feudal country in China history was established, and the great cause of reunification was completed for the first time. After the establishment of the Qin Dynasty, Li Si was promoted to prime minister. He continued to assist Qin Shihuang and made great contributions in consolidating the Qin regime, safeguarding national unity and promoting economic and cultural development. He suggested that Qin Shihuang abolish the enfeoffment system, which led to the feudalism and long-term struggle, and implement the county system. Divide the whole country into 36 counties (later increased to 4 1 county), counties and townships are directly under the jurisdiction of the central government, and palace officials are appointed and removed by the central government. The central government has three officials and nine ministers in charge of state affairs. This set of feudal centralization fundamentally eradicated the scourge of vassal state separatism and played a positive role in consolidating national unity and promoting social development. Therefore, this system has been used for nearly two thousand years in the feudal society after Qin Dynasty. After the reunification of the Qin Dynasty, due to the long-term division of the vassal States in the past, the language and characters were very different, which was extremely unfavorable to national unity and economic and cultural development. Reese and Didi put forward a unified script to Qin Shihuang and personally presided over the work. On the basis of Qin script, he abolished variant forms, simplified glyphs, arranged radicals, and formed Xiao Zhuan (also known as Qin Zhuan and Si Zhuan) with simple strokes, standardized form and convenient writing, as the standard script. He also personally wrote a song "Cang Xie" with Xiao Zhuan, which was promoted to the whole country as a model. The appearance of Xiao Zhuan is a great progress in the history of Chinese character development. Lu Xun said that Lisi was "outstanding" in the history of China literature. Unfortunately, most of the calligraphy has been lost in the flood season. At present, the Museum of Chinese History also has a collection of stone carvings inscribed by Li Si, and Daimiao Temple in Taishan, Shandong Province has fragments of imperial edicts with Li Si's seal script on them. Although these stone carvings have been seriously damaged, they are the earliest stone carvings in China and are really rare treasures. Reese has also made great efforts and contributions in unifying laws, currencies, weights and measures, and train tracks. In addition, the well-known "burning books to bury Confucianism" is also an extraordinary measure suggested by Li Si to crack down on Confucian scholars' perversion, slander political affairs and consolidate centralization. This played a positive role in the historical conditions at that time, but after all, it was a catastrophe in the cultural history of our country, which seriously damaged the cultural classics of the pre-Qin period. In 2 10 BC, after the death of Qin Shihuang, Reese, in order to protect his vested interests, echoed Zhao Gao's forged testamentary edict and made his youngest son Hu Hai emperor. After usurping power, Zhao Gao plotted a conspiracy, framed Reese for "rebellion" and punished him with five kinds of torture, such as flogging (tattooing on his face), flogging (cutting off his nose) and broken tongue. Reese spent most of his life pursuing legalism. Later, Ying Zheng, the king of Qin, was reused. With his outstanding political talent and foresight, he helped the king of Qin to complete the great cause of unifying the six countries and conformed to the trend of historical development. After the establishment of the Qin Dynasty, Li Si was promoted to prime minister. He continued to assist Qin Shihuang and made outstanding contributions to consolidating the Qin regime, safeguarding national unity and promoting economic and cultural development. He suggested that Qin Shihuang abolish the enfeoffment system and implement the county system. He also put forward the suggestion of unifying the characters, and then made great efforts in unifying laws, currencies, weights and measures, and car tracks. These measures were guided by legalists to strengthen centralization and absolute monarchy. In his later years, although Li Si pushed the legalist thought to the extreme, he was only a proposer, not a complete executor. Moreover, Reese has completely changed at this time. He wrote "This Book" because "A Er Yi wants to be tolerant". At this time, Reese has no ambition of "ruling the country according to law". He no longer represents the Legalists. Therefore, it is debatable whether Lisi's later thoughts should be included in the legalist system. So, in the final analysis, Reese is still the most complete executor of legalism.