[Objective] The impacts of targeted poverty alleviation policies on the happiness index of farmers in soil erosion areas were studied, in order to provide a scientific reference for sustainable development in poverty area.[Methods] The assessment index system of farmers' happiness index at Shuangbai County of Yunan Province was established, and entropy method and weighted summation model were used to evaluate the farmers' happiness index under the influence of targeted poverty alleviation policies.[Results] Per capita disposable income, marriage satisfaction and ecological environment satisfaction were the top there among the farmers' happiness index evaluation indicators. Most of farmers had a higher degree of recognition for targeted poverty alleviation, with an average satisfaction of 67.55 points. However, there were significant differences in the perception of policy among farmers. The satisfaction of income increase and decrease, policy consequence, and policy promotion were the key factors affecting the overall satisfaction of farmers in Shuangbai County with regard to targeted poverty alleviation policies. The average happiness index of farmers in Shuangbai County was 65.64 points, and the difference in happiness index of farmers in each township was relatively small, which maintained between 59~71 points.[Conclusion] In the future, farmers' happiness improvement and poverty alleviation should be regarded as the key breakthrough point in Shuangbai County, and targeted poverty alleviation policies would promote sustainable development in poverty area.