Cold-rolling mill base plate replacing device and method in mode of adjusting rolling line elevation through base plate

The invention relates to a cold rolling mill backing plate replacing device in a rolling line elevation adjusting mode, which comprises a main beam, end beams, fixing plates, supporting lug seats, supporting lugs, adjusting bolts and hooks, the two ends of the main beam are symmetrically connected with the end beams, the bottoms of the end beams are fixedly connected with the fixing plates, the tops of the two ends of the end beams are symmetrically connected with the supporting lug seats, and the supporting lugs are arranged on the supporting lug seats. The supporting lugs are rotationally connected with the supporting lug seats through short shafts, the bottom ends of the short shafts are connected with nuts, the nuts are arranged in grooves in the end beams, the supporting lugs are in threaded connection with adjusting bolts, the size of the fixing plate is the same as that of the base plate, and screw holes consistent with the base plate are formed in the fixing plate; and the distance between the two fix