A cutting-off and material returning device for cutting off automobile door glass guide rails comprises a base, a clamping mechanism, a cutting-off mechanism and a material returning mechanism. The clamping mechanism comprises a clamping oil cylinder, a sliding block, a movable clamping block and a clamping assembly. A clamping oil cylinder piston rod is fixedly connected with one end of the sliding block, and the other end of the sliding block is fixedly connected with the movable clamping block through a movable clamping block mounting seat. An upper wedge and a lower wedge are fixed to the upper portion and the lower portion of the movable clamping block correspondingly. The clamping assembly comprises an upper knife, a middle shaping plate and a lower knife. The middle shaping plate is fixed to a mounting frame. The upper knife and the lower knife are connected to the upper portion and the lower portion of the middle shaping plate in a floating mode correspondingly. The front end of the movable clamping block corresponds to the middle shaping plate. The upper wedge and the lower wedge correspond to the upper portion of the upper knife and the lower portion of the lower knife respectively. The cutting-off mechanism comprises a cutting-off oil cylinder and a cutting-off knife. The material returning mechanism comprises a material returning oil cylinder and a material returning rod. According to the cutting-off and material returning device for cutting off the automobile door glass guide rails, structure setting is ingenious, feeding is convenient, material returning is smooth, non-deformation of cut-off products can be guaranteed, and an automatic material returning function can be completed after cutting-off.