Abstract: The paper designed an expert system for automatic analysis of test cases, according to the feature of the test cases and the test sequence, researched on the rule base and reasoning mechanism which were the core of expert system, implemented the automatic analysis of test cases for CTCS-3 train control system, proposed to convert the test sequence into XML script and designed the key marker of the XML which was convenient for computer automatic analysis. The binary search algorithm was used to find the data segment of test sequences and test cases in vehicle data, improve the efficiency of analysis of the expert system. The results showed that the efficiency and accuracy of automatic analysis of test cases could be improved.