Abstract: The mechanical characteristics of the outer skin and inner pulp of corn straw are quite different. In order to improve the accuracy of the simulation results of corn straw, a method of establishing the refined simulation model of corn straw based on discrete element method（DEM） was proposed, and the simulation models of straw with and without stem nodes were constructed. Through the Plackett-Burman test and steepest climbing experiment, the uniaxial compression simulation test of the stalk without stem nodes model was carried out. It was determined that the main factors affecting destructive power of particles were sliding friction coefficient of outer skin-inner wall, the collision recovery coefficient of inner wall-inner wall, and static friction coefficient of inner wall-inner wall. The orthogonal test determined the optimal parameter combination to be 0.28, 0.29, and 0.23. The straw with stem nodes model was used to verify the shear test. The results showed that the shear resistance of simulation and physical tests were 132.29 N and 131.36 N, respectively. The error was 0.93 N, which indicated that the optimal parameter combination had healthy accuracy. The research results can provide reference for the optimization design of critical components such as straw returning devices, biomass materials molding devices, and feed processing devices.