The invention discloses a using method of a vehicle-mounted inflatable tent. The using method comprises a front arch inflation portal frame and a back arch inflation portal frame. The two inflation portal frames are connected through a plurality of transversely-arranged auxiliary supporting columns. The tent is characterized by further comprising a cuboid box body, the box body is wrapped by a canvas with one side capable of being opened, an inflation cushion comprises two identical belt bodies, and each belt body comprises an upper layer and a lower layer, wherein the upper layer and the lower layer are arranged in an integrated mode, the upper layer is black, a first opening and a second opening are formed in the side face of the belt body, an air inlet pipeline is arranged at the first opening, a joint is arranged at an inlet of the air inlet pipeline, the joint comprises a plurality of expansion joints which are located on a thread cap, an expansion pipe fixed to the air inlet pipeline and the head of the expansion pipe, are in an inverted conical shape and are distributed in the circumferential direction, the tail of the expansion pipe is in threaded connection with the screw cap, and a screw plug is installed in the second opening; the two belt bodies are symmetric about the box body and the middles of the two belt bodies are hinged to the box body. The tent can protect people against dampness when the people have a rest at night.