A high-efficiency medicinal-soil separation device was designed to address the challenges of separating fritillary bulbs from soil particles with similar sizes and the low recovery rate in existing fritillary bulb harvesters. Key parameters affecting performance and their value ranges were determined based on kinematic and dynamic analyses. A discrete element method and multi-body dynamics（DEM-MBD） coupling-simulation model was constructed. Central composite design（CCD） experiments were conducted with sieve inclination angle， crank radius， crank speed， and medicinal-soil roller speed as experimental factors， and recovery rate and separation efficiency as evaluation indexes. Analysis of variance（ANOVA） was performed on the results of CCD experiments to establish regression models between recovery rate/separation efficiency and significant factors. The model was solved with the multi-objective grey wolf optimization （MOGWO） algorithm to obtain the optimal combination. Results showed that increasing crank radius and crank speed improved both recovery rate and separation efficiency， while increasing sieve inclination angle had opposite effects. Excessive inclination caused material blockage at the front end， hindering rearward movement， though soil continuously sifted downward during operation. The optimal combination of parameters was the sieve inclination angle of 1.6°， crank radius of 39.7 mm， crank speed of 332 r/min， and soil-crushing roller speed of 284 r/min， achieving a recovery rate of 93.72% and separation efficiency of 92.09%. The results of bench verification under identical conditions showed that the recovery rate and separation efficiency was 91.05% and 90.17%， closely align with the simulation-optimized outcomes with a relative error of less than 3%， meeting the requirements for fritillary bulb-soil separation and fully validating the practicality of the dual-layer vibrating separation device designed.