Abstract: Due to the requirement of automotive motors on high speed, high integration, and high efficiency, high-speed permanent magnet flat-wire motors are being utilized increasingly in electric vehicles. However, with the increase in speed and integration, the alternating current losses and the core eddy current losses also increase, leading to an increase in motor temperature rise and a decrease in efficiency. To solve the problem, an efficient heat dissipation structure was proposed for motor stator oil cooling, cooling the stator core directly with oil channels, and cooling the end windings directly with two end oil spray rings. Based on a field-circuit coupling method, a model of permanent magnet flat-wire motor was established with a maximum featuring speed 20000 r/min and a peak power 94 kW to analyze the losses in the winding, core, and magnets under levity operation condition. And, the impact of the spray ring structure and the oil channel arrangement on the temperature rise of the motor was studied based on the thermal network and finite element method. Simulation results show that the average temperature of the winding can decrease by 8.76% and the average temperature of the stator core can decrease by 14.77% with an optimized spray ring arranged 15 conical sunk holes. Using a stator core with interleaved structure, the average temperature of the winding can decrease by 16.89% and the stator core can decrease by 16.42%. Finally, a motor temperature rise test was arranged for effectiveness validating of the stator oil-cooled heat dissipation structure of the stator oil-cooled heat dissipation structure.