Abstract: As a special way of automatic block, virtual block is used to divide the track section by virtualized logic section instead of the actual track occupancy detection equipment. This is of great significance to the harsh natural environment and difficult maintenance and maintenance of the alpine railway. In view of the characteristics of the next generation train control system, this paper studied on the virtual block technology of the alpine railway. The logic realization of interval security protection function under the condition of virtual block was analyzed under the condition of train occupancy check function and vehicle ground communication failure. According to the research of virtual block technology, in the case of train - ground communication failure, the paper took the blocking setting of the interval virtual section as an example, using the basic concept of colored Petri net and the CPN Tools modeling and simulation tool to analyze the blocking function. Based on the verification results, the model is analyzed and corrected to ensure the correctness of the logic function of the model.