Reynolds averaged Navier-Stokes (RANS) equations, energy equation and V2f turbulence model equations governing the flow field of the rotor frame, magnetic yoke and the pole, the stator were solved with finite volume method(FVM) based on unstructured mesh. The MRF(multiple implicit rotating frame) method was used to simulated the rotating motion of the rotor frame, magnetic yoke and the pole. The flow characteristic of different parts was analyzed. The influence of the gap size between insulating layer of bar core, the gap size between insulating layer of pole and coil to the temperature distributions on the solid parts was studied. The results show that the temperature on the windward of the pole is lower than the temperature on the leeward. With the gap size between the insulating layer of bar and core varying from 0.0mm to 0.3mm,the temperature of insulating layer of bar rise increases 9.2 degrees, So the gap size is important for the life of insulating layer. With the gap size between the insulating layer of pole and the coil varying from 0.25mm to 0.75mm, the temperature of coil increases 16.5 degrees. The results provide a reference for the rational design of the gap size.