Does the social security of Foshan Nanhai and Shunde need to be transferred?

I can tell you clearly that Nanhai and Shunde are both districts of Foshan, which have been co-ordinated at the municipal level, so the medical insurance relationship already belongs to a co-ordinated area, and there is no need to handle any transfer relationship. However, the medical insurance cards are still in the hands of all districts, so it is impossible to transfer the money from the medical personal account in Nanhai to Shunde, because the medical insurance cards in the two regions are different. Nanhai's medical insurance card is earmarked and can only be used to buy medicine in designated hospitals and pharmacies. Shunde's medical insurance card is not a medical card at all, but a bank card (UnionPay card of credit cooperatives). As long as you are insured, the Social Security Bureau will transfer the money to your card next month, and the money inside is at your disposal, which is very flexible.

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