Abstract: Institutional maturity is a concept of absolute and relative internal unity. The evaluation of institutional maturity can be carried out from the aspects of value performance, governance function, result effectiveness and ecological adaptation. The internal logic of institutional maturity and governance capacity modernization is shown as follows: On the one hand, institutional maturity lays the foundation for the modernization of governance capacity; On the other hand, modernization of governance capacity mapping institutional maturity. In the process of the development of the socialist system with Chinese characteristics, only by realizing the balanced adaptation between the maturity of the institution and the modernization of the governance capacity, and promoting the resonance between the growth of the system and the improvement of the capacity, can the institutional advantages be better converted into the governance effectiveness.