The utility model discloses a multipurpose straw crashing device. For meeting the requirement of a plurality of processing modes after crashing straws, the device is provided with a material outlet on the lateral end face of a screw shell, the tail end of a screw blade integrated shaft is welded with a material port subsidiary rod, and a screw blade integrated shaft flange is arranged on the screw blade integrated shaft. A diving key type coupling band is arranged on a screw mandrel, and the meshing and the separation with the screw blade integrated shaft flange are regulated by a control threaded rod and a control spring. The straws after being crashed and kneaded are thrown into a screw groove by the rotation of a crashing roller, are pulled to one side intensively by a conveyer screw and are pulled out of the material outlet by the assistance of a material port auxiliary rod to be stacked with the strip shape, thereby facilitating picking up pressed compacts to supply the pressed compacts to a straw power plant to be used for fuel. The screw groove is torn down, and the control threaded rod is loosened to cause the diving key type coupling band to be separated from the screw blade integrated shaft flange to throw the straws after being crashed and kneaded into the field. The structure of the device is simple, and different functional modes are convenient to change.