In order to reduce the mechanical damage of sunflower seed during its harvest and storage, and provide the theoretical foundation for the design of related mechanical devices, was studied the mechanical properties of sunflower seed. According to the geometrical dimensions and the mechanical parameters, which obtained from the experiment, we established the physical model and the finite element calculation model of sunflower seed. By the method of finite element analysis, not only analyzed the failure modes of sunflower seed under different compression loads and compress methods, but also the regularity of distribution of its stress and strain. By comparing the results of experiment and finite element simulation, we confirmed the feasibility of the model. The results showed that the anti-extrusion capacity of sunflower seed is anisotropic,along the directions of X, Y and Z, its elastic modulus are EX=64.01 MPa, EY=23.63 MPa, EZ=101.8 MPa, respectively. Under the same pressure, sunflower seed is most likely to rupture in horizontal direction and least likely to rupture in the perpendicular direction. Different loading directions lead to different failure modes, the perpendicular loading tends to cause local cracks and rupture, while the horizontal and transversal loading lead to the seed cracks along the crevice of the cotyledons. Besides, instability failure might happen under the transversal loading.