Can self-employed people apply for social security cards?

Individuals or individual industrial and commercial households can apply for social security cards.

If you are registered in Shenzhen, you can go directly to the Social Security Bureau with the receipt of social security photos, a copy of your ID card and a bank card (state-owned bank, like China Construction Bank). Non-household registration, bring business license, organization code, social security photo receipt, copy of ID card and copy of bank card to the Social Security Bureau.

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