Abstract: The geometric model and the finite element model with the measured results for breeding wheat grain were established. The stress distribution of breeding wheat grain was analyzed under different pressing locations and different pressing loads by applying the finite element method. The mechanical properties of breeding wheat grain under different pressing locations and different pressing loads were obtained， which could be provided as mechanical parameters for further study on mechanical properties， damage mechanism of breeding wheat grain and optimization of threshing machine. It could be concluded that fracture position and fracture direction of breeding wheat grain were consistent with the finite element analysis results after the comparison was made with the model calculation and the experimental results. When the compression load was applied to the seed abdomen， the macroscopic fracture of the seed presented stress cracking along with the abdominal sulcus， and when the compression load was applied to the top of the seed， the macroscopic fracture of the seed presented crack which began at the both sides of bottom， and then intersected at the top of the embryo and the endosperm symbiosis， finally， extended downward along with the middle of the embryo. Therefore， the macro fracture of the seed was caused by the internal cracks.

Key words: breeding wheat grain, mechanical properties, finite element analysis