Background: There is limited knowledge on the mediating role of different health risk behavior on the relationship between social capital, socioeconomic status (SES), and health-related quality of life (HRQoL) in Chinese older adults. We conducted this study to (a) investigate the condition of health risk behaviors of the Chinese elderly, and (b) assess the relationship between SES, social capital, health risk behaviors, and HRQoL. Methods: A sample of 4868 adults aged 60 years and older were included in this study, from the China's Healthrelated Quality of Life Survey for Older Adults 2018. Participants' demographic characteristics, SES (education level, family income), health risk behaviors (smoking, alcohol consumption, physical inactivity, unhealthy dietary behavior, unhealthy weight, and sleep disorder) were collected. Social capital and HRQoL were assessed by the 16-item Personal Social Capital Scale (PSCS-16) and WHOQOL-Old, respectively. Structural equation modeling (SEM) was applied to examine the associations between variables. Results: The proportion of smoking, alcohol consumption, physical inactivity, unhealthy dietary behavior, unhealthy weight, and sleep disorder were 32.1, 36.3, 62.5, 45.7, 31.8, and 45.5%, respectively. Significant differences were observed in education level, family income, and social capital between elderly individuals with and without each of the six health risk behavior (all p-values < 0.05). Elderly individuals who reported smoking, physical inactivity, unhealthy dietary behavior, and sleep disorder had significantly lower HRQoL than those without these unhealthy behaviors (all p-values < 0.05). SEM analysis showed that SES and social capital positively associated with alcohol consumption. Social capital negatively associated with smoking, physical inactivity, unhealthy dietary behavior, and sleep disorder. SES negatively associated with smoking, physical inactivity, unhealthy dietary behavior, unhealthy weight, and sleep disorder. Smoking, physical inactivity, unhealthy dietary behavior, and sleep disorder correlated with poorer HRQoL. Conclusions: Chinese older adults demonstrated a high incidence of health risk behaviors, especially for physical inactivity (62.5%) and unhealthy dietary behavior (45.7%). Social capital and SES were correlated with the elderly's HRQoL, as well as with the health risk behaviors. Health risk behaviors played potential mediating role on the relationship between social capital, SES, and HRQoL in Chinese older adults.