Abstract: The traditional methods of software development couldn’t meet the requirements of high security and integrity of safety critical system. The article proposed the method of SCADE-based safety software development, analyzed the principle, process and application methods of SCADE. The ZC of Urban Transit was taken as an example, through modeling and verifying the train management functions of ZC, it was proved that this method provided a new method which could efficiently ensure the high security and integrity of safety critical system.