Abstract: In order to analyze the influence of the surface pressure of the train on the air inlet and outlet of the traction converter and the cooling effect of the traction converter during the operation of the high-speed electric multiple units(EMU), the aerodynamic model of the open line operation of the train is established. The pressure distribution characteristics of the high-speed EMU running at the speed of 350 km/h are obtained by numerical simulation. The results show that the air inlet and outlet of the traction converter are all negative pressure, the average pressure difference between the air outlet and inlet is negative, which is conducive to the ventilation and heat dissipation of the traction converter. Then, according to the structure characteristics of the traction converter, the simulation models of the liquid cooling subsystem and the air cooling subsystem are established respectively, and the insulated gate bipolar transistor(IGBT) component temperature rise of the main inverter assembly, rectifier assembly and auxiliary inverter assembly, as well as the temperature rise of the electrical components such as transformer and reactor are obtained. Finally, the accuracy of the simulation results and the cooling effect of the traction converter are verified by the temperature rise test. The calculation of pressure characteristics and temperature rise of the traction converter has certain significance for the development of high speed EMU.