The utility model discloses a from DC power supply case of taking drainage mechanism, which comprises a box body and a box door, the box in be equipped with control circuit and battery, the intercommunication has drainage channel between the top surface of box and the bottom surface, and during drainage channel located the lateral wall of box, the top surface of box was equipped with the aqua storage tank, and the bottom surface and the drainage channel of aqua storage tank communicate with each other, the bottom surface of aqua storage tank be middle high height, structure that left and right sides height is low, drainage channel's top lie in the lower of left and right sides camber of aqua storage tank, solved the obscure problem of original DC power supply case radiating effect.