Working in one company, can I be a supervisor in another company?

According to your description, I will make the following analysis for you from the legal point of view: According to the law, the supervisor must be the shareholder of the company or the employee representative of the company. However, the law does not prohibit employees of one company from serving as supervisors in another company. Finally, you can refer to the Company Law of People's Republic of China (PRC) to understand the relevant legal provisions involved in this solution.