The utility model discloses a curved device is cooked over a slow fire to U type bolt, include and install hydro -cylinder, guiding mechanism and vice base in proper order on main base that the tailpiece of the piston rod head of hydro -cylinder is connected with the connecting rod, follow longitudinal center line and set gradually terrace die, concave wheelset, direction slider, die on vice base, concave wheelset sets up to a pair of, should set up respectively on the longitudinal center line both sides concave round, the terrace die passes through U type head to be connected with the link drive, and the direction slider sets up to a pair of, and this slides respectively to the direction slider and sets up on the longitudinal center line both sides, and perpendicular longitudinal center line direction fixed mounting has a guide bar on every direction slider, and every guide bar both sides is provided with a regulation lead screw respectively. The utility model discloses a device adapts to the work piece of different specifications, not only enables U type bolt and reaches and once cook over a slow fire the type of curving, has improved U type bolt greatly and has cooked over a slow fire curved quality and production efficiency.