Objective To study the status and influencing factors of social isolation among colorectal cancer patients with an ostomy, and to provide a reference for helping these patients return to society. Methods By convenience sampling method, 277 colorectal cancer patients with an ostomy were selected to fill out the demographic questionnaire, the General Alienation Scale and the Social Impact Scale. Results The patients scored (2.98±0.82) points in social isolation, and (2.92±0.60) points in social impact. The results of multiple linear regression analysis showed that social impact, primary caregiver, type of ostomy, number of hospitalization were main influencing factors of social isolation (all P<0.05). Conclusion Social isolation of colorectal cancer patients with an ostomy is above medium level, and individualized interventions should be given to patients whose parents are the main caregiver, who have a temporary ostomy, and who are frequently hospitalized, to help mitigate social isolation in the patients.