VariOus types of unccrttainties exist in thC assessment of etffects of climatic change on hydroligyand water resource. Based on the Monte Carlo and nonparametric me0hods.the uncertainties of modelDarameters and runoff are studied and estimated in this papaer.The results of case study indicate that runoff is more sensitive to variation in precipitation than to increase in temperature.The smaller the runoff coefficient is, the larg-er the runoff vary. If considering significannce leVel as 5% and the worst climatic scmario. the future peak dischargemavincrease by 50% in the southern part of China,which will seriously affect flood protection works.