Abstract:  Focusing on the problem that the safety and efficiency of train operation was affected directly by the accuracy and reliability of the Speed Measurement and Positioning System, this article proposed a design method for the model of Speed Measurement and Positioning System based on SCADE, introduced the method of requirement modeling and model verification, analyzed a model of speed measurement and positioning. The model of Speed Measurement and Positioning System was established by SCADE. Simulation and verification proved that the safety requirement of the System was completely satisfied.