Abstract: The efficiency of the underground drainage system in coal mines directly affects the production safety and economic benefits of coal mines. The existing multi-level relay drainage system in mines does not fully consider the peak and valley features of electricity bills and the safety constraints of the drainage system required by the Coal Mine Water Prevention and Control Regulations. It is difficult to achieve integrated safe and economic operation of the entire system. In order to solve the above problems, based on the avoiding peaks and filling valley strategy and dynamic programming method, an optimization strategy for multi-level relay drainage system in mines under the time of use electricity price is proposed. By considering the multi-level series structure, water inflow, and drainage capacity of water pumps, a mathematical model of a multi-level relay drainage system in coal mines is established. Based on the strategy of avoiding peaks and filling valleys, with the lowest electricity cost as the objective function and constraints such as water level in water tanks, drainage capacity of water pumps, and coal mine safety requirements, a multi-level relay drainage system optimization problem based on time of use electricity price is constructed. The solution algorithm based on dynamic programming method is provided. Taking the 4-level drainage system of a certain mine as an example for simulation analysis, the results show that this strategy can effectively control the underground water level and ensure that the water level is at a reasonable height. When the electricity price is high, the number of drainage pumps opened is very small or zero, and the water tank is in a high water level state. When the electricity price is low, the number of drainage pumps opened is larger, and the water tank is in a low water level state. This strategy can improve economic benefits while ensuring the production efficiency and safety of coal mines.