In view of the serious heating of the key components such as the radiator of the power module in the intermediate DC link of a locomotive converter, the direct current copper bus bar and the supporting capacitor, and the excessive temperature inside the cabinet, through analysis and test to find out the causes of the overheating, an effective scheme to solve the problem was put forward from the design point of view, and the effectiveness was achieved through test and comparison. This type of converter has accumulated nearly 1 000 units, and the overall operation was in good condition.