Objective To explore factors associated with advance care planning (ACP) engagement using the COM-B model in advanced lung cancer patients, and to provide references for clinical intervention decision making.Methods Using convenience sampling method, 317 advanced lung cancer patients were selected and completed a battery of questionnaires to measure their ACP engagement, ACP knowledge, attitudes and beliefs, resilience, etc.The influencing factors of ACP engagement were analyzed using the COM-B model.Results The ACP engagement score was （67.37±6.14）.A hierarchical linear regression showed that the length of cancer diagnosis, capability as ACP knowledge and resilience, motivation as ACP beliefs, ACP motivation, death attitude (the dimension of natural acceptance), anxiety and depression, and opportunity as social support, were factors influencing ACP engagement in advanced lung cancer patients (all P＜0.05), which could explain 50.4% of the total variance.The variance explained by capability, motivation and opportunity factors were 18.6%, 18.4% and 3.4% respectively.Conclusion The level of ACP engagement in patients with advanced lung cancer is relatively low, and mainly affected by capability and motivation factors, but slightly by opportunity factors.Medical staff should enhance ACP knowledge and resilience of patients with advanced lung cancer, arouse their ACP beliefs and motivation, adopt positive death attitude, alleviate anxiety and depression, and increase social support, thus to improve their engagement in ACP.