The performance of harvesting equipment affects the quality of bales. The physical properties （geometry and density）, contact properties （static friction coefficient, dynamic friction coefficient and collision recovery coefficient） and mechanical properties （blade elastic modulus and stalk deflection） of alfalfa materials were tested. Using the discrete element method, the clover stalk discrete element model was constructed based on the flexible fiber particle model, the clover blade discrete element model was constructed based on the flexible thin shell particle model, and the stalk and blade joint model was constructed based on the linear elasticity model. Aiming at the results of stalk resting angle, stalk three-point bending, blade slip angle and blade cylinder compression test，Plackett-Burman experiment, Steepest ascent experiment, center composite experiment and single factor experiment were used to calibrate the mechanics and contact parameters of stalk and blade that affected the simulation results. The results showed that the simulation stalk deflection was equal to the mean value of physical experiment. The relative error between the resting angle of simulated stalk and the mean value of physical experiment was 0.46%. The relative error between the compression density of simulated blade cylinder and the mean value of physical experiment was 0.82%. The relative error between the simulation blade slip angle and the physical experiment average was 0.15%. The calibration parameters can truly reflect the material characteristics of alfalfa, and the research results can provide theoretical basis and model basis for the optimal design of alfalfa harvesting machinery.