The invention discloses a train brake pad abrasion detection method. The method is characterized by comprising the steps that an image containing a train brake pad and a light transversal is collected; the light transversal on the image is detected; the train brake pad is subjected to edge locating with the light transversal as a parameter; the thickness of the train brake pad is calculated by combining calibration data and edge data obtained by means of edge locating of the train brake pad, and then the thickness of the train brake pad is obtained; the thickness is compared with the standard thickness of the train brake pad, and then abrasion data of the train brake pad are obtained. According to the train brake pad abrasion detection method, the light transversal is formed by being projected onto the train brake pad, and the thickness of the train brake pad is calculated in combination with the calibration data; the thickness of the train brake pad is compared with standard thickness data after being obtained, and then the abrasion data of the train brake pad are obtained. By the adoption of an image collection mode, the detection efficiency is improved, the image collection accuracy is controllable, there is no need to rely on manual experience, and the detection accuracy is higher.