Objective This study designed a self-assessment questionnaire drawing on the core entrustable professional activities (EPAs) indicators for residents. It aimed to explore its application value in evaluating the internship outcomes of clinical medicine students and provide a reference for competency-based reform in clinical internship teaching. Methods A questionnaire survey was conducted. The self-designed questionnaire was adapted from the core EPAs indicators for residents. A total of 283 undergraduates from the eight-year and five-year clinical medicine programs of Peking University's enrolled in 2018 participated in this study. Surveys were administered before and after their clinical internship. Self-assessment results pre-internship and post-internship were compared using the Mann-Whitney U test. Results Compared to pre-internship, the proportion of students self-assessing at level 3 (expected to perform with indirect supervision) increased for all indicators except recognition and management of critical illness. The highest increase was observed for case presentation, reaching 85.6% (131/153). Statistically significant differences (all P<0.05) were found in the self-assessment results for eight indicators: patient consultation, test selection/interpretation, diagnosis and differential diagnosis, case presentation, identification and management of general clinical problems,basic procedures, informed consent, and clinical teaching. For example, for patient consultation, the post-clerkship proportions for level 1 (unable to perform), level 2 (expect to perform with direct supervision), and level 3 were 0, 13.7% (21/153), and 85.0% (130/153), respectively, compared to pre-clerkship proportions of 0.8% (1/128), 35.2% (45/128), and 53.1% (68/128). Among these eight indicators, the first six had explicit teaching requirements during the internship, while the last two did not. No statistically significant differences (all P>0.05) were found in self-assessments for seven indicators: treatment decision-making, medical documentation, recognition and management of critical illness, patient transfer and handover, health education, breaking bad news, and response to public health event. For example, for treatment decision-making, the post-internship proportions for level 1, level 2, and level 3 were 9.2% (14/153), 53.6% (82/153), and 35.9% (55/153), respectively, compared to pre-internship proportions of 5.5% (7/128), 57.8% (74/128), and 21.1% (27/128). Among these seven indicators, the first four had explicit teaching requirements, while the last three did not. Conclusions Clinical internships contribute to enhancing students' clinical competencies. The self-assessment questionnaire designed drawing on core EPA indicators for residents can effectively reflect internship outcomes. Well-defined teaching requirements combined with sufficient clinical practice help improve the clinical abilities of medical students.