Abstract: In order to solve the problem of test case editing and maintenance in automatic test of train operation monitoring device (LKJ), this article used the methods of key information abstraction and graphical modeling to study the automatic test case generation technology of LKJ software. Through module partition, parameter design and program flow chart modeling of test cases, batch generation of test cases was implemented. This technology has been applied in LKJ15S automated simulation test system, proved that it can improve the efficiency of test case writing and reduce 90% of redundant use cases.