In order to explore the mechanism of the role of social support in the relationship between anxiety, depression and sleep quality, the study used a multi-stage whole cluster random sampling method to select 950 rural older adults in County C of Anhui Province, and conducted questionnaire surveys and data collection using survey tools such as the Pittsburgh Sleep Quality Index, the Generalized Anxiety Scale-7, the Patient Health Questionaire-9 and and the Social Support Rating Scale. The results showed that the anxiety score of elderly people in rural areas was 5.356.15, the depression score was 6.616.97, the sleep quality score was 8.144.78, the social support score was 36.258.32; anxiety, depression, and sleep quality were positively correlated (β = 0.399, 0.375, P<0.01); and the mediation effect test showed that social support played a partial mediating role in the effect of anxiety on sleep quality, and depression on sleep quality (P<0.01). Enhancing the level of social support can help improve the sleep quality of anxious and depressed rural older adults.