Objective　To study the effects of CBL teaching mode on treatment plan making process among orthodontic postgraduates. Methods　Totally 42 junior and senior orthodontic post-graduates were randomly divided into 2 groups （21 per group） named as experimental group and test group. Each group was further divided in to 3 teams involved in CBL and traditional teaching. Six cases of the same type malocclusion were selected each time; after 4 teaching cycle， test scores of two groups were analyzed with SPSS 19.0. Results were shown as mean ± standard deviation and t test and χ2 test were applied to evaluate the rationality and accuracy of treatment plan made by students. Survey questionnaire were issued to teachers and students after class and the assessment results of CBL teaching mode were summed up. Results　Test scores were （88.61±8.34） in experimental group and （76.13±8.59） in control group with significant differences （t=3.16，P=0.01）. Pass rate of two groups were 96.12% and 87.51% with significant differences （χ2=4.76，P=0.02）. During the first teaching program， accurate rates of experimental group and control group were respectively 31.00% and 36.70% and ra-tionality were 33.31% and 33.30%. During the second teaching program， accurate rates of experimen-tal group and control group were 68.80% and 45.70% and rationality were 62.72% and 43.37%. During the third teaching program， accurate rates of experimental group and control group were 89.70% and 51.20%， and rationality were 95.00% and 66.70%. During the fourth program， accurate rates of ex-perimental group and control group were respectively 97.80% and 55.30% and rationality were 98.30% and 75.60%. Conclusions　CBL teaching mode is helpful to improve the students' ability of analyzing clinical cases and making more accurate and rational treatment plan， however the increasing teaching cost and the course load are also involved.