A new type of steel plate turtleback defect correction program is introduced,using one upper roller and two lower rollers together to form a set of concave and convex roller mechanism,the upper roller can be adjusted by the screw mechanism to adjust the amount of underpressure,and the two sides of the frame can be moved axially to adjust the spacing between the two lower rollers.It can correct the turtle-back de-fects of U-beam after forming,and can be integrated in the production line for online correction to ensure the precision of steel strip or U-beam of steel plate under the line.