How many times do scientific research units recruit a year?

Twice a year. According to the official information released by People's Republic of China (PRC) and Ministry of Human Resources and Social Security, scientific research institutions are public institutions, and the recruitment of public institutions is generally twice a year, once in spring and once in autumn. Scientific research units refer to organizations specializing in scientific research and technology development, including universities, research institutes, laboratories, enterprise R&D centers, government agencies, etc.