10mm。 Smashing experiment has been done with help of smashing devices of the stalk macerator which self-designed. With shell angle, feeding velocity and distances of rotatory blade and fixed blade as test elements, with the smashing performance and power requirement as test index in the test, the mathematical model of the smashing capability and power consumption is established. Along with the feeding velocity increase, the shell angle increase and distances of rotatory blade and fixed blade reducing, the smashing power loss increases, and the smashing performance enhances. Using the regression equations and the priority target law, the parameter optimized design has been carried on. The result is as follows: the shell angle is 70°, the feeding velocity is 46.5m/s, the distance of rotatory blade and fixed blade is 10mm.