Abstract: In view of the increasing demand for high-efficiency forage grass grinders in China’s cattle and sheep breeding industry in China, a hammer shaft type forage crushing mechanism is designed, which mainly consists of hammer, mounting plate, axial crushing rotor and sieve. The crushing mechanism is designed by using a straight-knife hammer, and the theoretical model of crushing operation is established, and the blade, crushing speed and feed rotation speed are designed and calculated. Through the joint simulation of Adams and Simulink, the acceleration time is 0.35 s, maximum load of the hammer is 4 478.5 N, maximum deformation of the hammer is 36.1 μm, the hammer stress is concentrated at the pin shaft hole, and the maximum stress is 64.3 MPa. Static analysis of the hammer structure by ANSYS and checking of the hammer strength is performed to meet the strength requirements. The mode analysis of the designed crushed rotor by ANSYS Workbench shows that the crushing rotor is most prone to displacement deformation at the hammer, the first 4-order natural frequency of the crushing rotor is much greater than the excitation frequency, and the resonance probability is very small. The crushing performance of the prototype is tested through the test, and the average crushing efficiency of the prototype is more than 25 m~3/h, achieving the expected design goal.