Abstract: The causes of overheat of electrical room of model WK-35 excavator were analyzed. In view of problem that cleaning or replacing air filter to reduce temperature of electrical room of excavator waste time and energy labour at present, a solution was proposed through to adding a control circuit and time delay relay into main circuit of axial fan. The solution can realize the axial fan rotates reversely, and dust and debris clogging in filter would be sucked out effectively, so as to achieve increasing of air flowing, reducing temperature and solves the problem of overheat of electrical room.