Can I still receive social security and medical insurance if I am a foreigner?

To receive pension and enjoy medical insurance, you must be a citizen of China and have obtained social security before you can enjoy it. You are a foreigner, and dual nationality is not allowed in China, so you automatically lose your China nationality, and you can no longer enjoy China's pension and medical insurance. You can come back to social security to get back the amount paid by individuals in your personal social security.

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