Liquid injection coupling device

The utility model provides a liquid injection coupling device which comprises a box body, and the box body is provided with a mounting hole and a liquid injection hole. The mounting hole is used for mounting an ultrasonic probe, and a certain gap is reserved between the transmitting end face of the ultrasonic probe and the fitting opening end face of the mounting hole; and the liquid injection hole is used for injecting liquid into the gap, and when the attaching opening end face of the mounting hole is attached to the surface of the rail welding seam, the injected liquid enables the transmitting end face of the ultrasonic probe and the surface of the rail welding seam to be coupled. Liquid injection coupling is carried out through the designed liquid injection coupling device, water can be injected into the gap in a flowing mode all the time, the problem that the space between the ultrasonic probe and the rail bottom slope surface is not filled can be effectively solved, the problem that coupling between the