[Objective] A scientific and reasonable post-evaluation index system for soil and water conservation project benefits was established, in order to provide a scientific post-assessment basis for ecological management of small watersheds.[Methods] According to the comprehensive analysis of the characteristics of soil and water conservation engineering in small watersheds and the key factors affecting the efficiency of soil and water conservation projects, 13 key indicators for post-evaluation of soil and water conservation project were identified and selected, to establish a post-evaluation index system. Analytic hierarchy process(AHP) and the entropy method were used to improve the weight of the evaluation index. Combined with the evaluation index data, the index evaluation criteria was applied to improve set pair analysis model and analyze the post evaluation of project benefits.[Results] The improved set pair analysis model showed that the water conservation benefits, ecological benefits and social benefits in the evaluation index system were generally at the level of 2, and the effectiveness of watershed management was significant, and the potential for development was great.[Conclusion] The research demonstrates a new method to effectively evaluate the benefit of soil and water conservation projects in small watersheds. The new method is applied to the post-evaluation of soil and water conservation project benefit on the basis of constructing the post-evaluation index system, which basically achieves the expected research purpose.