International students pay social security in China.

After you come back from studying abroad, as long as you don't start a formal job, if there is no company to provide you with social security, you can only go to the place where your account is located and where your files are stored. Generally speaking, it was left by local talents. If you don't plan to work for a long time, I don't think it is necessary to pay the social security yourself, because if you work, the social security will be borne by the company until you find a job and then pay it in full. Personally, I think I can find a job within one year.

Further reading: How to buy insurance, which is good, and teach you how to avoid these "pits" of insurance.