C3+ATO system plays an important role in controlling train operation and its function is related to the safety of train automatic operation. A simulation and verification method based on timed automata is proposed to verify the function of high-speed railway C3+ATO system. The functional requirements in the C3+ATO system specification are extracted and the timed automata models are established and then the timed automata network model is formed. The message sequence charts are generated and system safety, reachability, existence are verified. As a result, the models meet the functional requirements of the system which provide theoretical reference for the subsequent C3+ATO system design and development, test and measurement, practical application and related specification improvement.