To evaluate the effect of CBL mode to making diagnosis and treatment plan for resident doctor who were being trained for pediatric dentistry. Methods: With Completely randomized way, 54 resident doctors were divided into two groups, which were taught with CBL mode and traditional teaching mode separately. Examination paper test and questionnaire survey were accomplished after the teaching. Research Data were analyzed with t-test and χ 2-test. Results: There were no significant difference between two groups of students’ examination pass rate. Scores, diagnostic accuracy and rationality of treatment plan of the experimental group were higher than that of control group, P＜0.05. The questionnaire showed that CBL mode was positively evaluated by students of experimental group, but at the same time, it also increased the burden of course learning. Only 55.56% students in questionnaire survey thought the CBL mode was helpful to improve theoretical examination performance. This proportion was not ideal and needed be improved in the future. Conclusions: CBL teaching is advantageous to increase the diagnostic accuracy and rationality of treatment plan, and improve the students’ competency of case analysis. CBL mode should be selectively applied in the teaching process, and combined with the actual situation of students. Meanwhile, its limitations need to be recognized, which can avoid increasing the students burden overly and reduce the students' interest in learning.