Objective To explore the mediating effect of community′s self-efficacy for preventing social isolation between degree of frailty and quality of life of the community-dwelling elderly. Methods From January to March 2018, a random sample of 535 elderly selected from the community in Dandong of Liaoning were surveyed by Community′s Self-efficacy Scale for preventing social isolation (CSES), the Comprehensive Frailty Assessment Instrument (CFAI) and 12-Item Health Survey. The data collected were analyzed to establish a structural equation model. Results The score of community′s self-efficacy for preventing social isolation, degree of frailty, and quality of life were (12.833±6.514), (53.042±16.014) and (61.276±30.649), respectively. Degree of frailty was negatively correlated with community′s self-efficacy for preventing social isolation (r =-0.460, P =0.000) and quality of life (r =-0.559, P =0.000); Community′s self-efficacy for preventing social isolation was positively correlated with quality of life (r =0.599, P =0.000). Community′s self-efficacy for preventing social isolation played a partial mediating role between degree of frailty and quality of life among the community-dwelling elderly. Conclusion Community′s selfefficacy for preventing social isolation plays an intermediary role between degree of frailty and quality of life, and degree of frailty mainly affects quality of life of the elderly through indirect action of community′s self-efficacy for preventing social isolation.