In order to effectively improve the ventilation performance of permanent magnet synchronous traction motor used in the rail transit，this paper，taking a 600 kW permanent magnet synchronous traction motor as an example，and based on computational fluid dynamics ( CFD) and the basic theory of heat transfer，establishes the three dimensional physical model under its ventilation scheme for the analysis of temperature field. Applying the finite volume element method，each part of the permanent magnet synchronous traction motor was numerical analyzed. And the temperature distribution of its internal components was summarized in order to optimizing. It provides the theory basis forimproving the permanent magnet traction motor cooling performance as well as the accurate calculation for temperature field of the permanent magnet traction motor with larger capacity.