Due to small volume, high torque density, high loss density, cooling difficulties of direct-driven permanent magnetsynchronous traction motor, on the basis of the four angle cooling structure, three kinds of reciprocating cycle cooling structures weredesigned for a 190 kW direct-driven permanent magnet synchronous traction motor. The three kinds of cooling structures were calculatedwith fluid field, and an optimal cooling structure was selected for the analysis of temperature field. A prototype was manufactured and atemperature experimental platform was developed. The experimental results were validated temperature rise was reasonable and the motorwas stable and reliable.