The invention discloses a closed equipment cooling system. The closed equipment cooling system comprises a closed box, a refrigerating device, an electric heater and a control circuit. The refrigerating device comprises a compressor, a condenser, a throttling component and an evaporator. Main components of closed equipment and the refrigerating device are installed in the closed box. The control circuit comprises a temperature sensor and a controller for controlling the refrigerating device and the electric heater to work, and the signal output end of the temperature sensor is connected with the controller. When the closed equipment cooling system works, the electric heater is turned on first, the temperature in the closed box is made to rise to make condense water on the surfaces of elements of the closed equipment evaporate, and then the closed equipment is started. The fault rate of the equipment can be lowered, and the safety level can be increased.