The invention discloses a winding device on a wrapping machine. The winding device comprises a support platform, a motor, a bearing, a driving pulley, a driven pulley, a rotating pulley, a two-sided synchronous belt, a positioning cylinder, a charging wheel and synchronous belt tension pulleys, wherein the rotating pulley is rotationally arranged on the support platform through the bearing; the charging wheel is arranged on the rotating pulley; an output shaft of the positioning cylinder is propped against the side wall of the rotating pulley, the driving pulley and the driven pulley are arranged on the support platform, the two-sided synchronous belt surrounds and connects the driving pulley and the driven pulley and forms an upper driving side belt and a lower driving side belt which move in opposite directions, the synchronous belt tension pulleys are arranged on one side of the upper driving side belt and one side of the lower driving side belt, the upper driving side belt is meshed with the rotating pulley, a rotating shaft of the motor is fixedly connected with the driving pulley, and the upper driving side belt of the two-sided synchronous belt drives the rotating pulley to rotate when the motor drives the two-sided synchronous belt to move. The winding device does not require human assistance in a winding process and is high in working efficiency.