Recent years, with increasing urban population, urban traffic's pressure is increasing. Urban mass transition is in the period of rapid development. The new generation of train control system-CBTC(Communication Based Train Control)is applied to the constructions of urban mass transition. In CBTC system, vehicle onboard system plays an important role about security and effectiveness of train. The function of vehicle onboard system is directly connected with the traffic safety. Therefore, before

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... he vehicle equipment system puts into operation, we must complete rigorous tests and verify the functions. In the test, the test cases directly affect the quality of test works. So this paper is focused on test methods and specific test case for vehicle onboard system. The functions of vehicle onboard system should be modular. Modularization of the functions could reduce the number of test cases and improve the efficiency of the test.