Abstract: The Park-level Integrated Energy System (PIES) is characterized by diverse load demands and complex energy supply equipment. In order to solve the problems of low energy efficiency and unreasonable energy structure in the energy supply of PIES, a cascade optimization method of PIES considering dynamic energy efficiency model was proposed. Firstly, according to the principle of energy cascade utilization, the load of PIES is subdivided according to energy grade. Secondly, the dynamic energy efficiency model of cascade energy equipment is established by analyzing the characteristics of energy equipment efficiency that changing with load rate. Finally, with the goal of the lowest daily operating cost of the PIES, the PIES cascade optimization operation plan is solved. The results of calculation examples prove that the proposed cascade optimization method can effectively improve the level of energy efficiency utilization, reduce operating costs, and provide theoretical and technical guidance for the rational energy use and operation management of PIES.