Can I buy Chongqing social security repeatedly for old-age insurance?

Can't buy any more. At present, there is no national social security net, and your hometown can give it to you. If you want to enjoy the pension insurance benefits after retirement in your current work unit, you must pay the pension insurance in this place for a total of 15 years, and because the registered permanent residence is not here, you can't pay it in the form of individual contributions, which means you must have a work unit to pay it for 15 years. If it is less than 15 years, and your hometown has given you 15 years, then after retirement, you can only go back to your hometown to enjoy the old-age insurance benefits. The part of repeated payment can be refunded. Of course, only the personal account can be refunded, so there is not much money.

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