Based on the tracking survey data of hydropower project migration in Jinsha River basin from 2014 to 2018,this paper analyzes the relative poverty characteristics of hydropower migrants and the causes of poverty using multi-dimensional poverty measurement method and spatial regression discontinuities. The study found that the relative poverty characteristics of migrants are mainly developmental poverty and consumption based poverty. First,the production of most immigrant families was seriously damaged by the reservoir construction. Restricted by natural conditions and human capital,immigrant families not only found it difficult to maintain their original livelihood,but also were blocked in the process of livelihood transformation,resulting in difficulties in the construction of family livelihood after immigration,and therefore fell into developmental poverty. Second,the construction of hydropower has increased the market participation of migrant families. After immigration,the increase of per capita living cost up to more than 2000 RMB is very unfavorable to the accumulation of family capital,which aggravates the developmental poverty of the immigrant group and increases the possibility of returning to poverty in the future. Third,these characteristics of poverty are more obvious in part-time working families and families with low to moderate income levels. Policy improvement should focus on the identification and governance of such poverty,effectively alleviating the widening development gap between and within groups,and avoiding new risks brought by policy failure.