The hammer crusherhashigh productivity, small energy consumption, safety use, easy maintenanceand wide range of applications. When design hammer crusher we need to payparticular attention to the design of wearing parts, including hammer, bearings,grate bar, impact plate; this paper mainly describes the design of grate andimpact plate. Grate is a set of steel bars of equal size to control thegranularity of broken materials open pit mining machine; When coarsely crush brittle materials, the gapof grate bars should be higher than 1.5 to 2 times of the maximum particle size;when fine crush brittle materials, it should be 3 to 6 times of particle size;grate gap should be along the movement direction of materials, that is, the gapshould be gradually extended from insider gradually along the direction ofhammerhead line speed so that the qualified products are successfully excludedwithout blocking. The spread pattern of grate bars should be vertical with themovement direction of hammer head. In addition, the gap between the two gratesis usually 60mm. The role of impact plate is to re-bounce broken materials tocrushing plate for re-crushing; in order to obtain better crushing effect, thematerials should be vertically collided to the surface of counter plate. Thesurface of counter plate includes mansard type and involute type. Mansard typeplate has simple structure, but cannot guarantee that the most effectiveimpacting; involute impact plate materials impact materials vertically withbetter effect. However, due to the involute impact board is difficult tomanufacture, we usually adopt polyline impact plate. In short, we need tobase on safety use and convenient maintenance so that design crusher with lowercost and superior performance.