Abstract: To implement the interconnection and interoperability of urban rail transit signal systems and provide three-dimensional analysis for operational scenarios under cloud platforms, this paper designed a cloud based signal system interconnection and interoperability testing platform. The paper implemented software part through C language programming, adopted secure and defensive programming technology and code error detection to prevent systematic failures, and adopted the fault-safety design principle and a two times two out of two architecture design for the hardware part, which improved the safety and reliability of the system, and tested and verified the interface conversion and on-site device driver functions of the testing platform by building a sand table model. The results indicate that the interconnection and interoperability function of cloud based signal systems can be achieved, and this testing platform can be used for testing signal systems.