Objective To explore the relationships among social isolation, depression, loneliness negative feelings and quality of life in the community-dwelling elderly, and to further analyze the mediating effects of depression and loneliness on the relationship between social isolation and quality of life. Methods A total of 592 community-dwelling older adults were investigated using the Lubben Social Network Scale-6, Geriatric Depression Scale, UCLA Loneliness Scale and the 36-item Short Form Health Survey Scale. Results The score of social isolation, depression, loneliness and quality of life of the community-dwelling elderly was 14.95±4.58, 5.19±3.13, 42.06±8.53 and 113.02±10.56 respectively.The score of social isolation was negatively correlated with the score of depression and loneliness, and was positively associated with quality of life score, while the score of depression and loneliness were negatively correlated with quality of life score (P＜0.01 for all). Social isolation could affect quality of life directly (β=0.558), it could also influence quality of life indirectly through the partial mediating roles of depression and loneliness (β=0.367). The mediating effects of depression and loneliness accounted for 24.86% and 14.81% of the total effects respectively. Conclusion The risk of social isolation in the community-dwelling elderly is high.Social isolation could influence quality of life of the elderly directly or indirectly through the negative feelings of depression and loneliness.It is necessary to promote the active integration of the elderly into society, so as to improve their negative feelings and quality of life.