In view of the shortages existing in the present stressor-response model, the stressor-response model of lake was improved by nonparametric LOWESS robust regression. Taking Taihu Lake as a case, a nonparametric LOWESS robust regression stressor-response model of total phosphorus and chlorophyll a was constructed. The reference condition concentration of total phosphorus in Taihu Lake was deduced as 0. 018 mg/l, and the 95% confidence interval was 0. 013-0. 030mg/l by bootstrap method. The rationality of the result is verified from multi angle.