In the course of the social development of Yi people, the family branch organization as a traditional system had existed for a long time and assumed all-round social functions. Ever since the targeted poverty alleviation campaign, most impoverished Yi people have moved out of mountain regions and into resettlement communities, and their living environ- ment and habits have changed significantly. Nevertheless, the family branch tradition still affects all aspects of their com- munity life in the resettlement sites. We chose the Muendi community of Chengbei Town and the surrounding representa- tive relocation sites in Zhaojue County of Liangshan Prefecture as examples and conducted field interviews, case investiga- tions and literature researches, so as to analyze the impact of family branch system on Yi people′s relocation, political par- ticipation, social communication, life and social production in the course of community reconstructions. We determined the auxiliary roles of the family branch system in the course of community reconstructions, and proposed ideas on ways to change family branch′s roles, regulate its goals, make use of its powers and promote its culture, so that we could better guide relocated Yi people to integrate into their new community life.