To legally get a job in China, need to comply with the requirements of Chinese law on foreign workers: age 24-60 years, Higher education (not below the bachelor) and 2 years of work experience. You also need to be healthy enough, to undergo a medical examination.
In the presence of all required documents and the right of the employer to hire foreigners, he can get for you a work permit and an invitation. These documents can get a work visa outside of China (most likely in your country). Last, you should get a working residence and this work quietly in the Chinese company, which settled.