Objective To investigate the status of social isolation among community-living oldest-old adults and to identify the inf-luencing factors. Methods A total of 411 community-living oldest-old adults in Shanghai were surveyed using the general information questionnaire, the Lubben Social Network Scale (LSNS-6), Activities of Daily Living Scale (ADLs), 5-Item Geriatric Depression Scale (GDS-5), Montreal Cognitive Assessment Basic (MoCA-B) and Social Participation Questionnaire. Results Fifty-four percent of the oldest-old were socially isolated.Regression analysis showed that education level, hearing status, activities of daily living, depression, cognitive function and social participation were factors influencing social isolation (P＜0.05 for all). Conclusion The prevalence of social isolation is relatively high in community-living oldest-old adults and affected by many factors.Special attention and interventions should be given to enhance their quality of life.