Objective To explore the influencing factors of active physical activity behaviour among community-dwelling fall risk older adults, so as to provide a reference for developing active physical activity program and promoting active physical activity behaviour in older adults.Methods Based on the Capability, Opportunity, Motivation-Behaviour (COM-B) model, a descriptive qualitative study was designed, and 16 community-dwelling older adults with fall risk were selected by using purposive sampling method to conduct semi-structured interviews, then the content analysis method was used to analyze the interview data and refine themes.Results Three themes and six sub-themes were extracted:capability factors (physically ability, mental ability), opportunity factors (the physical opportunities consisted of external environment and scientific and technological products, the social opportunities from the grandparenting and peer effects), and motivation factors (the spontaneous motivation of active physical activity behaviour derived from benefits of health and perceived happiness, and disease triggers and negative events were its reflective motivation).Conclusion Motivation of active physical activity behaviour among community-dwelling fall risk older adults still needs to be improved, and enhancing physical and mental abilities is a prerequisite and foundation for promoting their active physical activity behaviour.It is necessary to create more opportunities and environment to promote active physical activity behaviour of this population, and improve their physical and mental health.