[Objective] The applicability and uncertainty of HSPF model in tropical coastal basins was explored in order to provide scientific reference for the application of HSPF model in different basins and regions.[Methods] Taking the Sanya river basin located in the tropical coastal region as a study area, a HSPF model was established, and the flow from 2017 to 2019 was selected to calibrate and verify the model. The sensitivity of 8 parameters in the hydrological process was analyzed by Morris screening method, and compared with the relative sensitivity of parameters in different watersheds studied at home and abroad. Meanwhile, the uncertainty of the model under different rainfall conditions were analyzed by MC-LHS method.[Results] The HSPF model could simulate the actual hydrological process in the study area very well. The NSE of the periodic and validation period was 0.93 and 0.98 respectively, and the R_e was 0.87% and 0.21%, respectively. Among which, base groundwater recession was the most sensitive parameter, while the influence of lower zone evapotranspiration parameter and proportion of groundwater flow into deep was almost negligible.[Conclusion] The relative sensitivity of the parameters reflected the spatial differences. The uncertainty of model simulation is significantly correlated with rainfall, the greater the rainfall is, the greater the uncertainty and confidence interval of the model simulation are, and the more unstable the model is.