The invention provides an interface moisture-proof device, which relates to the technical field of power auxiliary equipment. The interface moisture-proof device comprises a sleeving piece, a tightening sleeve, a clamping sleeve and a jam nut, wherein the sleeving piece is also internally provided with a clamping platform. According to the interface moisture-proof device provided in the invention,a pin and a plug can be effectively protected through the sleeving piece; by using a tapered closing port between the tightening sleeve and the sleeving piece, the effect that the tapered closing port is tightened to the center and abuts against the periphery of the plug can be realized, and the sealing effect between the plug and an external environment is ensured; the clamping sleeve arranged on the periphery of the pin is tightly contacted with the sleeving piece, the sleeving piece and the clamping sleeve are tightly connected through the jam nut, the sealing effect between the pin and the external environment is ensured, and the external environment can be prevented from eroding a connection point between the pin and the plug; and as the clamping platform is arranged, axial positionsof the pin and the plug are ensured to be stable in the device, the moisture-proof effects of the interface are effectively ensured, and the service life of the pin and the service life of the plug are improved.