Numerical simulations utilizing the discrete element method（DEM）represent a robust approach for investigating the dynamic properties and displacement behaviors of subsoil seeds during the process of post-sowing suppression. The parameters associated with the soil-seed discrete element model played a crucial role in determining the accuracy of the simulation outcomes. However, the wet clay prevalent in the middle and lower reaches of the Yangtze River exhibited elevated water content and significant viscosity. Consequently, conventional soil parameters failed to adequately represent the physical characteristics of this wet clay, resulting in a lack of precise parameters for the discrete element model of wet clay-wheat interactions. The contact parameters of the wet clay-wheat interaction model during post-sowing suppression were calibrated. Initially, based on physical tests and significance analysis, the initial range of parameter values was determined, followed by the identification of parameters that exerted a significant influence on the natural accumulation slope coefficient. Subsequently, a regression model was developed to establish the relationship between each key parameter and the slope coefficient by using response surface methodology. This process yielded multiple superior combinations of soil-soil and soil-wheat parameters. Thereafter, the discrepancies in the force-displacement curves between actual compression tests and simulation tests were analyzed to select the optimal parameter combination. Finally, the accuracy of the parameter model was assessed by comparing the simulated values with the actual results from quasi-static compression tests, rolling compression tests, and field tests. The results indicated that the soil-soil restitution coefficient（CR1）, soil-soil rolling friction coefficient（RF1）, and soil-soil interfacial surface energy（SE1）significantly influenced the natural accumulation slope coefficient of wet clay（CS1）. Moreover, the soil-wheat static friction coefficient（SF2）, soil- wheat rolling friction coefficient（RF2）, and soil-wheat interfacial surface energy（SE2 ）also had a significant impact on the natural accumulation slope coefficient of wet clay-wheat mixture（CS2）. The optimal parameter combination was identified as follows：CR1 was 0.12, RF1 was 0.35, SE1 was3.90 J/m2, SF2 was 0.48, RF2 was 0.29, and SE2 was1.69 J/m2. Additionally, the relative errors for each validation test under the optimized model were 7.16% for the quasi-static compression test, 10.41% for the rolling compression test, and14.42% for the field test.