Abstract: In order to achieve the goal of "double carbon", the renewable energy in the Beijing-Tianjin-Hebei region has been continuously connected to the power system, which puts forward higher requirements for the flexibility of the power system operation. As a kind of adjustable resource which can make the power system realize the dynamic balance of supply and demand, the flexible resource is very important to the safe and stable operation of the power system. In order to further understand the impact of relevant policies on the development of flexible resources in the Beijing-Tianjin-Hebei power system, this paper constructs a system dynamics model, and designs policy regulatory factors from four aspects: thermal power flexible transformation investment, energy storage technology investment, incentive strength, and peak-valley electricity price. The development of power system flexibility resources is simulated under single policy scenario and combined policy scenario respectively. Finally, according to the simulation results, the corresponding policy optimization suggestions are put forward from three aspects: strengthening fiscal policy, perfecting science and technology policy, and perfecting mechanism design.