The invention discloses a gate threshold damage detection device which comprises a bracket, a water storage tank, a water inlet cylinder, a filtering device, a water pump and a control device. A baffle is disposed on the bottom of the water storage tank vertically. A plurality of drainage pipes with different heights are vertically disposed in the baffle. The top ends of the drainage pipes communicate with the water storage tank. The bottom ports of the drainage pipes define a circular table-shaped cavity. A camera is disposed on the bottom of the water storage tank in a sealed manner, wherein the lens of the camera is located on the upper part of the circular table-shaped cavity. When there is a need to detect damage to a gate threshold, the muddy water is filtered by the filter device and then is converted into pure water. The pure water is pressurized by the water pump and then is discharged from the drainage pipes. The muddy water in the baffle is diluted continuously so that the camera is in a pure water shooting environment. Thus, the gate threshold is captured to be detected at this time in order to ensure good picture definition and to clearly judge the wear position and wear degree of the gate threshold.