The research on the evaluation of later support effect of reservoir resettlement has greatly contributed to evaluating the realization of policies for reservoir resettlement in the later stage, providing a scientific reference for the adjustment of relevant policies. By combing the relevant investigation results and policies and integrating the economic,social, environmental and other factors, 5 first-class indicators and 28 second-class indicators are selected for the reservoir resettlement problem, and the evaluation index system of the later support effect is established. The weight and connection of each indicator in the evaluation system are determined by using analytic hierarchy process and set pair analysis method, the evaluation grade is calculated to quantitatively evaluate the support effect of reservoir resettlement in later stage. Taking Gansu province as the research object, the study evaluates and analyzes the later support effect of reservoir immigrants. The results show that the overall evaluation score of Gansu province is 0.420, rating as good level.The suggestions for the later support work are refined according to the results, which provides an objective and reasonable basis for exploring the later support mode of reservoir immigrants with local characteristics and further improving the production and living standards of immigrants.