What do you mean by the transition and non-transition of Shanghai social security three insurances?

This is a hard and fast rule. But there is no absolute.

Transition: Pay social security according to the minimum payment base stipulated by Shanghai.

No transition: pay social security according to your salary base. (Not less than the lower limit of the payment base stipulated by Shanghai)

I hope I can help you.

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