The hydrogen leakage detection and alarm processing system is established for the fuel cell (FC) power train lab to meet the hydrogen safety demand of the FC performance test and examination for the project named "Research and Development of the Vehicular Technology for the Fuel Cell City Bus" by Tsinghua University. The established hydrogen safety system includes the hydrogen supply system, hydrogen leakage detection system, alarm processing system, ventilation system, measures against electrostatic, thunder-arresting and explosion-protection, and the strict hydrogen operation rules. In this safety system, the explosion proof catalytic combustion sensors are used to detect the hydrogen leakage and the electrical control system is designed to process the alarm automatically. The hydrogen safety system plays an important role in the performance, examination of the FC and the assuring the personnel' s safety of the fuel cell power train lab.