Abstract: Hydrogen Fuel Cell Vehicles serve as an important solution for energy conservation and emission reduction in the transportation sector. Investigating the failure mechanism of the on-board hydrogen systems of HFCVs is of great significance for popularizing HFCVs and improving their safety. Taking the on-board hydrogen system and its components for commercial vehicles as the research object, this paper establishes a failure model of the on-board hydrogen system via dynamic simulation to simulate the failure behaviors of the hydrogen system under various working conditions. The results show that the relative displacement between the hydrogen storage cylinder and the binding belt reaches 6.816 mm, which creates a risk of separation and may easily induce impact failure. Under high-pressure operating conditions, the hydrogen storage cylinder and cylinder valve bear high loads, accompanied by local stress concentration, which is highly likely to cause structural damage. The primary failure mechanism of the on-board hydrogen system is ultimately revealed: when the system is subjected to vibration impact or the internal overpressure of components, the structural members endure high stress and sustained stress concentration. Structural failure occurs once the stress exceeds the yield limit of the material. The research findings can provide data support and theoretical guidance for the structural design and safety research of on-board hydrogen systems.