The utility model discloses a low-voltage power distribution box cooling system, and belongs to the field of temperature reduction and cooling devices. The system of the utility model comprises built-in fans located inside the box body and a cooler group of a large-power electronic device. The built-in fans are arranged above the cooler group; a group of air dampers capable of rotating transversely are arranged below the cooler group; one ends of the air dampers are in pin connection and fixed, and the other ends are rotatable ends; a support crossbeam is arranged outside the air dampers; screw rods are arranged on the support crossbeam; one end of each screw rod is fixed on the support crossbeam via a nut and the other end of the screw rod is connected with the rotatable end of the air damper; and the support crossbeam is fixed inside the power distribution box. As combination of adjustable screw rods and the nuts is provided, the inner structure of the device is not changed, the control line is not changed, and adjustable air amount needed for cooling is realized on the premise of increasing a speed-adjustable circuit, and the system of the utility model can be widely used in the design and manufacturing field of the low-voltage power distribution box.