The invention relates to the technical field of agricultural machinery, in particular to a potato depth limiting device with a function of row alignment detection. The potato depth limiting device comprises a depth limiting wheel, a depth limiting wheel fixing bracket, laser reflecting sensors, a lead screw, a lead screw fixing frame, a soil scraping plate, a rotating device, a guide shaft, a depth limiting device connection round pipe and a connection frame. The depth limiting wheel fixing bracket comprises depth limiting wheel connection plates, sensor fixing supports, a soil scraping platefixing plate and M14 threaded hole fixing plates. The depth limiting wheel connection plates are fixedly connected to the depth limiting wheel fixing bracket, the depth limiting wheel is mounted between the two depth limiting wheel connection plates, and the sensor fixing supports are fixedly mounted on left and right sides of the depth limiting wheel fixing bracket. When the depth limiting wheelreturns to the center of a potato ridge, the depth limiting wheel fixing bracket is aligned and gets rid of a sensing range of the laser reflecting sensors to cut off an oil circuit, then a hydraulicoil cylinder stops operation, a function of once row alignment guiding is realized, and finally, potato damage reduction, potato digging omission reduction and potato harvesting quality improvement are realized.