Abstract: To meet the need of fast delivery of reliable ATS software products for metro, an automated testing system for metro ATS software based scenario simulation was developped and the composition, main function design, testing environment deployment and configuration of the system are introduced together with test case design and testing process. The testing system is composed of a tested obejct server, a simulation integration server and a testing management server. By separating the simulation of the internal and external environment of ATS system, the complexity of the ATS software simulation test system can be reduced. The simulated testing environment is set up using virtual machine technology and test cases are designed based on scenario simulation according to the combination of ATS software function items with operational scenarios. So, the combination of multiple function items can be verified by using test cases based on one single scenario simulation. The testing efficiency of ATS software can be significantly improved by continuous optimization and reuse of accumulated test cases based on scenario simulation. In addition, the test report can also be generated automatically by the system. The process of automated test on ATS software is described in details by taking the project of upgrading the signaling system of Shanghai Metro Line 1 as an example.