Aiming at the problems of insufficient parameters and inaccurate simulation in discrete element simulation for Yunnan red clay soil, taking the red clay soil of sloping cultivated land in central Yunnan as the research object, the simulation model of the unconfined compressive strength test based on the EEPA model and the Bonding model was established by combining the unconfined compressive strength test and the discrete element simulation method, and the relevant parameters in the simulation model were calibrated. The maximum axial pressure of soil sample fracture in the unconfined compressive strength test was 431.19 N. The Plackett-Burman test was designed with the maximum axial pressure as the response value to screen out the factors that had a highly significant influence on the response value, and the optimal parameters of the highly significant factors were determined by the Steepest Ascent test and Box-Behnken test. The results were as follows: the normal stiffness per unit area of the Bonding model X1 was 3.14×108 N/m3, the critical normal stress X3 was 53 175.4 Pa, and the contact-plasticity ratio of the EEPA model X6 was 0.318 24. In the validation simulation under this parameter combination, the relative error between the maximum axial pressure and the test was only 1.71%, and the fracture surface of the bonding Bond was compared favorably with the test. The data obtained from the simulation were consistent with the test, indicating that the parameter combination was reliable and can provide a theoretical basis for the subsequent discrete element simulation of red clay.