The human activity which is characterized by underlying surface change is the core issues of the hydrological cycle study and has important effects on hydroelectricity, water resource management and economy sustainable development. This paper analyzed the variation trends of annual rainfall and runoff in Youjiang Hydropower Station catchment by trend analysis method. Based on the analysis of underlying surface changes, the runoff coefficients were also simulated by using multivariate statistical analysis and multivariate statistical analysis considering rainfall. The results showed that the trends of annual rainfall and runoff were consistent, the main influencing factor of annual runoff was annual rainfall, which made the model better when the rainfall was regarded as one argument in the rainfall-runoff regression model.