In the middle and late warring States period, the six eastern countries could not defeat Qin, so why not learn from Qin's reform?

Because the other six monarchs are not as sincere as Qin.

At the beginning of his accession to the throne, Xiao Gong was deeply saddened by the decline of the Qin Dynasty, so he made a decree to seek talents: "If there are guests and ministers, they can make a coup for Qiang Qin, and I will respect the officials and share the land with them equally." Wei Yang, a patriotic man, entered Qin and taught Xiao Gong to be overbearing. Xiao Gong was very happy and tried his best to make a reform.

In 356 BC and 350 BC, Qin Xiaogong appointed Shang Yang to carry out the most thorough reform. Shang Yang's political reform encouraged population proliferation, emphasized agriculture and restrained business, abolished the system of "being an expensive official", rewarded military service, compiled household registration and implemented the law of "tongzhi". At that time, Qin was vast and sparsely populated, Sanjin was vast and sparsely populated, and the people lacked fields. Therefore, Shang Yang suggested that Qin Xiaogong should adopt preferential policies for foreign immigrants to attract Sanjin people to reclaim wasteland in Qin.

In 350 BC, in order to deepen the reform and get rid of the interference of the old aristocratic forces, Qin Daliangzao (Shang Yang) proposed to move the capital from Yongcheng (now Baoji Fengxiang) to the newly-built Xianyang City, which was supported by Qin Xiaogong.

Wei Yang completely abolished the old stone-clearing system, established a new autocratic centralized system, and promoted the county system to strengthen centralized power, attaching importance to agricultural products, resulting in a prosperous scene of "giving enough to others". The people of the whole country are ashamed of private wars, thinking that the country is proud of its military achievements, and its combat effectiveness is constantly increasing. Wei Jun has been defeated in repeated wars, and Qin, a rich country in Qiang Bing, became the most powerful country at the end of the Warring States Period, and stood out in the west. Historical records record: "Nineteen years of filial piety, the son of heaven is a servant." King Xian of Zhou named Qin Jun as Fang Bo, which officially acknowledged his hegemony.