I used to work in my former factory and had social security. Now change factories and pay social security in this company. What procedures should I go through?

Is the company that insured you before in the same city as your household registration?

If you are not in the same city, you need to go through the transfer procedures.

Individual contributions are handled by the social security bureau where the household registration is located. You can open an account in the local social security bureau with your ID card and household registration book, and then handle individual payment.

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