To examine unreasonable plantation and severe soil and water and soil loss on sloping land in Yunnan Province, a research was conducted on the benefits of soil and water conservation under sweet maize intercropped with green pepper and grass strip. In June, July and August, runoff under intercropping treatment decreased by 29.08% and soil erosion, by 52.36%, as compared with sole cropping; total runoff for the treatment B(sweet maize+grass) decreased by 85.05% as compared with the treatment D(green pepper mono-cropping), and total soil erosion, by 62.58% and 63.34%, respectively, as compared with the treatments C(sweet maize mono-cropping) and D; and during rainfall of the highest intensity, runoff for the treatment B decreased by 75.29% as compared with the treatment D and soil erosion decreased by 81.36% and 98.34%, respectively, as compared with treatment C and D. The result shows that sweet corn intercropped with grass strip is an effective measure for sustainable use and protection of soil and water resources in a mountainous area.