The invention discloses a straw compressor. The upper end face of a base is fixedly connected with a first connecting plate, the upper end of the side wall of the first connecting plate is provided with a guide rail, the guide rail is slidably connected with a sliding block, and the sliding block is connected to one end of a horizontal section of a T-shaped plate, the lower end of the T-shaped plate is fixedly connected with a pressing hammer, and the other end of the horizontal section of the T-shaped plate is in threaded connection with a rotating rod. The straw compressor is simple in structure. By switching on an external power supply, a motor is controlled through positive and negative switching to rotate, the rotating rod is driven to rotate, the guide rail makes the T-shaped plate incapable of rotating, and the pressing hammer performs longitudinal motion and pushes a sliding plate to move to cut off straw; when the sliding plate moves from top to bottom, the straw is cut off again; when the sliding plate moves from bottom to top, a pressing plate squeezes and compresses the straw below the pressing plate. The straw compressor can cut off and compress the straw, effectivelysave storage space and reduce cost.