The invention relates to the technical field of steel plate deformation measurement and particularly relates to a steel plate deformation measurement device. The steel plate deformation measurement device comprises an automatic reading measurement instrument, an adjustable bracket, water level observation instruments and a water pipe, wherein the water level observation instruments include a water level observation instrument I and a water level observation instrument II, one end of the water pipe is connected with the water level observation instrument I through a connecting assembly, the water level observation instrument I is fixed on the automatic reading measurement instrument, the other end of the water pipe is connected to the water level observation instrument II through the connecting assembly, and the water level observation instrument II is fixed on the adjustable bracket; and a permanent magnet is arranged on the adjustable bracket and adsorbs a to-be-measured steel plate, and the water level observation instrument I and the water level observation instrument II are respectively arranged vertical to the to-be-measured steel plate. The steel plate deformation measurement device is simple in structure, convenient to assemble and use and low in cost, can be used for accurately measuring and is applicable to the measurement of the deformation of most steel plates.