Objective To investigate the levels and factors associated with frailty and social isolation in long-term survivors after allogeneic hematopoietic stem cell transplantation （HSCT）, and to provide reference for intervention. Methods A total of 312 patients who received HSCT beyond 2 years were invited to complete a general information questionnaire, the Fried Frailty Phenotype scale, Self-rating Depression Scale and the General Alienation Scale (GAS). Results The incidence of frailty in long-term survivors after HSCT was 26.9%, and the total GAS score was （39.53±7.24） points.Frailty was positively correlated with the GAS score (P＜0.01).Frailty, return to work or not, depression, and complications were influencing factors of social alienation （adjusted R2=0.451,P＜0.01 for all）. Conclusion Long-term survivors after allogeneic HSCT have high prevalence of frailty and severe social isolation.Frailty, not returning to work, depression and complications might cause or exacerbate their social alienation.Timely assessment and targeted interventions should be taken to ameliorate their frailty and social isolation.