Is it legal for foreign companies to pay social security by employers?

Legal. According to the provisions of Article 61 of People's Republic of China (PRC) Social Insurance Law, we can know that the social security payment of enterprises is to outsource the social security payment business to the human resources company for payment, and the company account is managed by the human resources company, that is, the social security account is managed by a third party, which belongs to the category of personnel outsourcing, and it is legal for the third party to pay social security.