The upper roller move vertically. The lower rollers can move horizontally. It has double functions of pre-bending and roll. And it can finish pre-bending and roll steel plate by feeding once. The three rollers are diving-roller. It can present skidding while rolling thin plates and enlarge the rolling scope, precision achieve ±0.2mm. The three rollers have brake devices installed while revolving. It can make sure precise position and safe work while rolling. It's controlled by micro-machine and has digital display, simply operation and high efficiency.