Abstract: Late-stage support plays an important role in improving the per capita disposable income of reservoir immigrants. Therefore, it is of practical significance to quantitatively analyze the present situation of income increase supported by reservoir resettlement in the later period and formulate reasonable planning suggestions. In order to reveal the lag effect of input indicators on the change of migrant income and reflect the actual performance level of late support, this paper calculates the lag period of input indicators by time difference correlation analysis method, and establish a DEA model of late support lag effect. From three aspects of resettlement quality, production conditions and capital investment, three sample counties in YF Citing Province are taken as research objects to study the support performance and lag effect of reservoir resettlement in the later stage. The results show that the post-migration support in YF city is not DEA effective, with the average comprehensive efficiency of 0.931 and the scale efficiency lower than the pure technical efficiency. It has the characteristics of low technical management level and excessive investment scale in the county, and the average efficiency will decrease by 0.5%～14.4% without considering the lag effect. The results of the study objectively reflect the situation of support in the later stage, and can provide a basis for the implementation and adjustment of the support policies in the later stage of migration.