Given the lack of accurate parameter values in discrete element simulation of sweet potato seedling mechanized recovery, a direct measurement and virtual calibration method was used to study the Discrete Element Method (DEM) simulation parameters of broken sweet potato stems and leaves. The intrinsic parameters, collision recovery coefficient and static friction coefficient of broken seedlings were acquired by physical experiments. Different parameter combinations were designed for DEM simulation. The intrinsic parameters of sweet potato leaves and other unmeasurable DEM simulation parameters were determined by stacking angle optimization simulation. Plackett-Burman test shows that the static friction coefficients of stem-stem and stem-steel and the rolling friction coefficients of stem-stem and stem-leaf all significantly influence the accumulation angle. The parameters that significantly influence the stacking angle of broken seedlings were sent to steepest ascent test and Box-Behnken test. The average stacking angle of 40.51° and the relative error of 0.972% indicate it feasible to calibrate DEM parameters by physical test and optimization simulation and the calibrated parameters can be used in DEM simulation of broken sweet potato stems and leaves.