In some provincial/regional markets dominated by hydropower in China, the economic operation of cascade hydropower is very important, and cascade hydropower has its unique physical characteristics, so it is necessary to carry out targeted modeling in the clearing model of power spot market. Therefore, in view of the fact that multiple hydropower plants share one reservoir in the process of cascade hydropower clearing, a power spot market clearing model considering one reservoir with multiple hydropower plants is proposed. The model aims to minimize the total power generation cost of the system. Based on the traditional power spot market clearing model, the abandoned water power, water level control and abandoned water flow constraints of one reservoir and multiple hydropower plants are embedded in the model. Adding the abandoned water flow restriction of hydropower plants to the optimal operation model of cascade hydropower can actually simulate the abandoned water behavior of hydropower plants and make the clearing result of cascade hydropower more reasonable. The IEEE39 standard node system is taken as an example to analyze and verify the proposed clearing model of electricity spot market for cascade hydropower with multiple plants in the same reservoir.