The invention discloses a bridge turning body device and a construction method thereof. The bridge turning body device is used for turning a bridge body alpha degrees, a pier stud is arranged below the bridge body, the bridge turning device comprises a lower support, an upper support, a bridge support, a rotating part, a polytetrafluoroethylene sliding plate, a pair of lateral air cylinders, two pairs of jacking oil cylinders, two pairs of supporting structures arranged oppositely and a steering device, wherein the rotating part is annular, is coaxially fixed to the lower surface of the bridgesupport, and is located on the upper side of the upper support; the polytetrafluoroethylene sliding plate is in an annular shape completely same as the rotating part and is spliced by a left semi-annular plate and a right semi-annular plate which are completely same; the pair of lateral air cylinders are respectively horizontal and can be detachably fixed in a first through hole; the inner side ends of the lateral air cylinders are connected with one semi-annular plate; the steering device can drive a driven gear to rotate horizontally. The device has the advantages that the device has a turning body capable of turning easily, the turning body is stable, and the cost can be reduced, and can be widely applied to the technical field of bridge turning body construction.