Objective To explore the influencing factors of physical activity among coronary heart disease patients after percutaneous coronary intervention (PCI), and to provide a reference for developing physical activity enhancement strategies to improve their physical activity level. Methods A descriptive qualitative study was designed based on the Social Ecological Model, then nineteen coronary heart diseasepatients after PCI were selected by using a purposive sampling method to conduct semi-structured interviews. Content analysis was performed to analyze the interview data and extract themes. Results Three themes and eleven sub-themes were extracted: individual factors (knowledge of physical activity, perceived value and risk of physical activity, disease status and physical symptom burden, psychological state, self-efficacy and motivation); interpersonal factors (family support, peer interaction, guidance from healthcare professionals); and environmental factors (physical environment, traditional cultural perceptions, healthcare institution and community service support). Conclusion Physical activity in coronary heart disease patients after PCI is influenced by factors at the individual, interpersonal, and environmental levels. Comprehensive intervention strategies should be developed by integrating influencing factors at all levels to improve the physical activity level of coronary heart disease patients after PCI.