Abstract: In order to reduce soil and water losses in sloping fields and improve sustainability on fragile slopes, the field experiment was conducted in 2001 and 2002, in Wanjiajing catchment, Yunnan and the effect of mixed grass strip on reducing water and soil losses in sloping fields was analyzed. Four treatments including Setaria sphacelata×Trifolium pratense(A), Festuca arundinacea×Trifolium pratense(B), Festuca arundinacea (C) and without grass strip(D), with three replications which the slopes range from 13.2% to 14%, were investigated. The contour grass strip with width of 0.5 m was placed at the bottom of each plots. Maize of 18 m² was planted at the upper of sloping fields of each plot. Runoff and sediment were collected during maize growing season (May to October). The results show that the water and soil losses of the mixed grass strip are less than that of the singled grass strip. The total amounts of runoff and sediment are significantly different among the four treatments with the order of D＞C＞B＞A. Compared with the treatment D, the runoff amounts of treatments A, B and C were reduced by 79.19%, 64.02% and 51.53%, respectively, the soil erosions are reduced by 92.04%, 84.49% and 78.70%, respectively. Mixed grass strip is in favor of increasing vegetation cover, plant height and grass root system. The better effectiveness of soil and water conservation is achieved when gramineous grass and leguminous grass are intercropped.