Abstract: In order to avoid insulation failure and inter-turn short circuit failure caused by partial overheating of submersible motor filled with water during operation and improve the reliability of motor operation, a 500 kW water-filled submersible motor is taken as an example, a three-dimensional global temperature field model of the submersible motor is established, including the cooler, the cooling water channels, and the external shield. The inner part of stator slot is simplified by the model, which considers the flow of cooling water in the stator groove, and the precision of temperature field simulation is further improved. Finally, the internal and external circulation cooling process of the submersible motor is simulated and the simulation results of the temperature field are verified by building a submersible motor experimental platform.