Shellfish culture heavy soils are suitable for the cultivation of marine organisms and are essential for the development of marine fisheries. To study both the interaction between heavy soil particles and that between the soil and soil-engaging components of agricultural machinery in shellfish culture, the simulation parameters in the model were determined. To study the interaction between soil particles in the viscous soil of shellfish culture with moisture content of 26.51% ± 1%. Discrete element method is used to establish the accumulation simulation experiment; the contact parameters between soil particles were calibrated. The response surface optimization technique was used to create the accumulation angle regression model. To study the interaction between the soil and soil-engaging components, the static friction coefficient between the heavy soil and soil-engaging components was determined by static friction experiment. The contact parameters between the soil and soil-engaging components were calibrated by the slope simulation experiment; the rolling distance regression model was established by response surface optimization methodology. The findings demonstrate that the optimized soil model can simulate the actual soil, and reflect the interaction between the heavy soil particles, soil, and the soil-engaging components of agricultural machinery, which not only provides a theoretical basis for the design and optimization of soil-engaging components of agricultural machinery in heavy soil, but also provides a new way for the research and development of agricultural machinery in a complex environment.