The ventilation network can be emerged in the urban traffic tunnel due to the existence of branch and auxiliary tunnel. In view of the different ventilation tasks, tunnel emergencyventilation system has different ventilation rate and power demand. How to design a suitable ventilation system for all of the ventilation tasks becomes a problem that urban traffic tunnel construction must carefully study and solve. Based on the theory of ventilation network, the paper discusses power matching method for the emergency ventilation system in urban rail traffic tunnel. In addition,the design for the emergency ventilation system in rail traffic is analyzed by taking onerail engineering as an example.