Abstract: Objective: To analyze the current situation of the advance care planning (ACP) readiness in the patients with advanced cancer, and to explore the influencing factors. Methods: From October to December 2024, a total of 234 patients with advanced cancer were surveyed using the general information questionnaire, the social support rating scale (SSRS), the general self-efficacy scale (GSES), the ACP cognition scale, and the ACP readiness scale. Results: The total score of the ACP readiness in patients with advanced cancer was (77.53±11.50), and ACP readiness showed positive correlation with social support, self-efficacy, and ACP cognition (r=0.308, 0.451, 0.655, all P＜0.01); the total effect of social support on ACP readiness was 0.433, with a direct effect of 0.127; the mediating effects of self-efficacy and ACP cognition in the relationship between social support and ACP readiness were 0.040 and 0.143, accounting for 9.24% and 33.02% of the total effect, respectively; the chain mediating effect of self-efficacy and ACP cognition in the relationship between social support and ACP readiness was 0.123, accounting for 28.41% of the total effect. Conclusion: The ACP readiness of patients with advanced cancer is above the medium level. Medical staff should pay greater attention to improving their ACP readiness, and develop scientific, personalized, and systematic intervention measures from the perspectives of social support, self-efficacy, and ACP cognition, so as to enhance their ACP readiness.