He'nan province locates in transition areas of both south climate to north climate and mountain to plain area.Influenced by special climate,geography environment and human being actions etc.,the situation of soil and water losses is serious and the productive conditions and ecological environment are fragility in these mountain areas.Basis on the analysis of harm of soil and water loss and the function of soil and water conservation to improve the productive conditions and ecological environment,the paper points out that soil and water conservation is the root to maintain agricultural sustainable development in mountain areas.The countermeasures of improve water and soil conservation and maintain agricultural sustainable development in mountain areas are prevention and protection,erosion control and construct farmland with high productivity by terracing on the slope,reinforce the projects of blocking sands and sluice and water system match on the slope,strengthen supervising and management and keep the new artificial water and soil losses within limits.