To study the possible impact of capacity mechanisms on China's electricity market, a triple equilibrium model based on Cournot equilibrium theory is established for the strategic behavior of oligarchs under the two capacity mechanisms of reliability option and strategic reserve. The model focuses on the impact of strategic behavior of power generation enterprises on power transaction and user cost under different capacity mechanisms. By using OMIE open data of the Iberian power market operator, the simulation verifies the mitigation effect of the capacity mechanism on market supply-demand relationship. The results also show that the introduction of a capacity mechanism only changes the way oligopoly enterprises exercise market power, and the ability of oligopoly enterprises to influence transaction price still exists. The two capacity mechanisms have certain limitations in different ways. This work is supported by the Science and Technology Project of State Grid Corporation of China "Research on Technical and Economic Characteristics and Operation Mechanism of Energy Internet" (No.1400-202057430A-0-0-00).