Objective : To explore the mediating effect of self-efficacy on family health and health literacy among middle-aged and elderly chronic diseases patients in rural areas, so as to provide a basis for developing targeted health literacy improvement strategies. Methods: Based on the publicly available 2021 "Survey of Chinese Residents' Psychology and Behavior" database, rural chronic diseases patients aged >45 years were selected as the study subjects. Data on demographic information, family type, and chronic diseases comorbidities were collected. The Chinese simplified Family Health Scale, General Self-Efficacy Scale, and Health Literacy Scale were used to assess family health, self-efficacy, and health literacy, respectively. Correlation analysis was employed to explore the relationships between variables, and the 4.1 Process program was used to analyze the mediating effect of self-efficacy on family health and health literacy. The Bootstrap method was applied to test the significance of the mediating effect. Results: A total of 449 participants were included, of whom 241 were male (53.67%) and 208 were female (46.33%). The majority (205 cases, 45.66%) were aged 60-<76 years. There were 168 cases (37.42%) with chronic disease comorbidities. The total score for family health was (37.96±6.25) points. The self-efficacy score was (27.28±5.40) points, the health literacy index was (27.72±8.08) points, and the health literacy proficiency rate was only 14.90% (67 patierts). Mediating effect analysis showed that family health could directly and positively influence health literacy, with a direct effect value of 0.090 (95%CI: 0.001-0.179). It could also indirectly and positively influence health literacy through self-efficacy, with a mediating effect value of 0.164 (95%CI: 0.099-0.234). The mediating effect accounted for 64.31% of the total effect. Conclusion Self-efficacy plays a positive mediating role between family health and health literacy among middle-aged and elderly chronic diseases patients in rural areas.