Based on the studies of the natural environmental structures of the Ba river basin in Luotian county, the different harnessing zones were divided and the harnessing patterns for optimization of the structures of agriculture and forestry were set up their benefits were demonstrated with emphasis on soil and water conservation. The severe soil erosion is in the central zone of Bahe River basin. The characters and patterns of soil erosion in this zone are related with local activities of agricultural cultivation. Following soil and water conservation the appropriate countermeasures on in this region is studied. To regulate the agricultural structure and prolong land covered periods were thought to be the most useful way to improving the ecosystem. At last the different effect about soil and water conservation were reached, the benefit were compared. On this study the author gave the conclusion: adjust agricultural structure plays important place in optimizing ecosystem on the hill soil erosion region.