With the grid connection of large scale distributed generations, the regulation and control of distribution network becomes more diversified. Under the circumstance, the key influence factors of the decoupling optimization and coordinated optimization of active and reactive power is investigated. Firstly, an analysis method considering the influence of the changing of power source, network, and load on the power optimization of distribution network is proposed for problem of the power optimization for distribution network containing distributed generation. Then, based on the two power optimization models, the interaction mechanisms between power optimization and grid price, network parameters and load are analyzed. And the mathematical expressions of line impedance ratio and load power factor to transmission power are given. In addition, the boundary conditions of two optimization modes are given qualitatively. At last, an improved IEEE?33 bus system is included to verify the impact of core influence factors for two power optimization modes on the total power generation cost and calculation time, including the feed?in tariff, the impedance rate and length of transmission line, the power factors and load.