Abstract: The present invention provides a welding seam tracking sensor, which belongs to the technical field of sensors, and alleviates the problem of detection performance reduction of a sensor. The welding seam tracking sensor comprises a sensor housing, a protection cover and a protection sheet; the protection cover is mounted on the bottom of the sensor housing, an air inlet is provided on the upper surface of the protection cover, and a blowing hole is provided on the bottom of the sensor housing. The air inlet and the blowing hole is closely connected; there is a visual hole and a laser hole in the bottom of the protection cover, a transverse slot is formed inside the protection cover, a socket is opened on the side wall of the protection cover, the protection sheet is inserted into the slot through the socket.