In order to explore the flow characteristics of the cooling structure (statorrotor ring gap+stator slots) under the ultrahigh speed, taken a rated speed 120 000 r/min ultrahigh speed PM motor as an example, and studies 3D fluid fields in the statorrotor narrow gap by computational fluid dynamics method with considering the influences of stator slots, axial flow and rotational speed on the flow field. It showed that taylor vortexs in the statorrotor ring gap will disappear for the slotting stator. Furthermore, a high rotational speed and axial flow will enhance the mixing degree of the air in the statorrotor ring gap and the air in the stator slot. The resulted provides a significant reference for the thermal design of rotor of the high speed PM motor.