To enhance the efficacy and quality of clinical internships and ensure a seamless transition into competency-based residency training, a reform in the pediatric internship program was designed and implemented. This program aimed to systematically improve the comprehensive competencies of medical students during their pediatric rotations. The redesigned curriculum is grounded in the principles of competency-based medical education (CBME), with explicit learning objectives targeting the development of six core competencies: professionalism, medical knowledge, patient care, communication and collaboration, teaching capability, and practice-based learning. The program is characterized by its clinical practice-centered approach, augmented by diverse pedagogical methods, and a robust assessment system combining formative and summative assessments. A study was conducted involving 62 eighth-year medical students undertaking their pediatric internship at Peking University First Hospital in 2023. Multiple data collection methods, including end-of-rotation examinations, structured questionnaires, and semi-structured interviews, were employed to evaluate the impact of the reformed program. Post-reform assessment results demonstrated a marked improvement in overall internship performance, with 79.0% of students achieving a final score above 85. Furthermore, 93.2% (40/43) of participants expressed satisfaction with the new teaching and assessment system, reporting significant enhancements in clinical reasoning, patient communication, theoretical knowledge, professionalism, and self-directed learning. The most highly valued components were teaching modalities embedded in routine clinical practice and formative assessment methods. Specifically, daily patient management and SOAP (subjective, objective, assessment, plan) case presentations were perceived as the most beneficial for competency development. In conclusion, the reform and implementation of this competency-based curriculum and evaluation system represent a successful endeavor in strengthening the holistic development of medical students during their clinical internships. This model effectively fosters clinical skills and comprehensive competencies in pediatric education and facilitates articulation with subsequent competency-based residency training, thereby offering a valuable reference for internship reform in medical schools across China.