为合理估算流域非点源污染营养盐输出负荷,针对广泛使用的输出系数模型方法,通过实测数据推算获得流域主要土地利用类型氮磷营养盐输出系数,并同时考虑流域降雨的空间差异,对模型结构进行了改进,并与GIS实现融合,构建半分布式的输出系数模型.利用该模型对太湖上游的西苕溪流域氮磷营养盐输出负荷进行了估算,结果显示,西苕溪流域TN输出负荷为2121.3 t,TP输出负荷为49.3 t,这为太湖流域非点源污染治理提供了参考,改进的输出系数模型具有很好的时空尺度适宜性和推广性. In order to reasonably estimate the nutrient export load of non-point source pollution in watershed, aiming at the widely used output coefficient model, the output coefficients of nitrogen and phosphorus nutrients of main land use types in the basin were obtained by measured data. At the same time, Structure was improved and integrated with GIS to construct a semi-distributed output coefficient model.Using this model, the output load of nitrogen and phosphorus nutrients in Xitiaoxi valley in the upper reaches of Taihu Lake was estimated. The results showed that TN output load in Xitiaoxi watershed was 2121.3 t, TP output load of 49.3 t, which provides reference for non-point source pollution control in Taihu Lake Basin. The improved output coefficient model has good spatio-temporal scale suitability and promotion.