A Content, Context, Connection and Researching, Reasoning, Reflecting (3C3R) model is a conceptual framework for problem-based learning (PBL) problem design. We introduced the 3C3R-PBL method into a pediatric teaching plan, and evaluated its effectiveness and feasibility. The 3C3R model was applied in a pediatric problem design teaching plan "why the lips turn purple when a baby is crying". All students were assigned either into a traditional PBL course or into a 9-step 3C3R model PBL course (3C3R-PBL). The performance outcomes of both groups were compared. For the PBL group, the proportion of students scoring ≥4 for content, context, and problem design connection, was 90.8%, 80.3%, and 64.5% respectively, while for tutors, it was 71.4%, 71.4%, and 28.6%; for researching, reasoning, and reflecting, the proportion of students scoring ≥4 was 81.6%, 55.3%, and 40.8%, while for tutors, it was 71.4%, 100%, and 57.1%. The learning difficulty was not considered high with only 31.6% of students and 42.9% of tutors rating the task as difficult. For the 3C3R-PBL group, the proportion of students scoring content, context, and connection, ≥4 was 100%, 98.4%, and 90.5%, while for tutors it was 100%, 100%, 83.3%; for researching, reasoning, and reflecting, the proportion of students scoring ≥4 was 95.2%, 88.9%, and 76.2%, while for tutors it was 100% for all 3 R components. Students and tutors were convinced by the content, case context, research process and reasoning process of both teaching plans, while scores for connection and reflecting were significantly improved when the PBL plan was amended by a 3C3R model (p<0.05) and the case learning difficulty was statistically increased (p<0.05). The 3C3R model, evaluated for the first time in China, was helpful for effective and reliable problem design in a pediatric PBL teaching plan for Chinese students.