This study takes the high slope of Maiwan Water Conservancy Hub in Tunchang County, Hainan Province as the research object, focusing on the challenges of identifying parameters for the unsaturated seepage intrinsic models. Utilizing wireless transmitter, data acquisition instruments, and other monitoring devices, on-site slope infiltration experiments were conducted. The collected monitoring data were combined with the differential evolution method to perform a global inversion of the Van Genuchten model's parameters ( $\alpha$, $n$, ${\theta }_{\text{s}}$, ${\theta }_{\text{r}}$, $K_{\text{s}}$). A finite element model was established using PLAXIS software for numerical simulation, analyzing the variation patterns of simulated values and comparing them with measured values to validate the reliability of the inverted parameters. The results demonstrate that the numerical simulations driven by the inverted parameters exhibit high consistency with the measured data, with errors at each depth remaining within 5%. Experimental verification confirms the accuracy of the numerical simulations, providing a parameter basis for unsaturated seepage studies in tropical slopes and a reference for determing unsaturated hydraulic parameters in similar soils.