Objective To explore the application of Mini-Clinical Evaluation Exercise (Mini-CEX) in training the diagnostic thinking ability for clinical interns. Methods 83 interns who came to the First People’s Hospital of Lianyungang for clinical practice in June 2015 were divided into the experimental group (45 interns) and the control group (38 interns) according to their schools. The two groups received the same clinical teaching according to internship program of five-year clinical medicine

while the experimental group had to take a weekly Mini-CEX training in clinical sections. The diagnostic thinking ability of the two groups was measured by the Diagnostic Thinking Inventory in Chinese version at the beginning and the end of the internship respectively. SPSS 21.0 was applied to processing the data. Measurement data were expressed as mean plus or minus standard deviation（ s）

and t test was used in the comparison between groups. Results At the end of the internship

the total score of diagnostic thinking

the score of knowledge structure in memory and the score of flexibility in thinking of the experimental group were higher than scores at the beginning statistically

and the experimental group had a statistically higher score than the control groups in knowledge structure in memory [(69.36±4.28) vs.(66.95±4.78)

P=0.018]. Conclusion Mini-CEX training can enhance the clinical diagnostic thinking ability of interns by improving their knowledge structure in memory.