The route optimization problem for road networks was applied to pedestrian flow. Evacuation path networks with nodes and arcs considering the traffic capacities of facilities were built in metro hubs, and a path impedance function for metro hubs which used the relationships among circulation speed, density and flow rate for pedestrians was defined. Then, a route optimization model which minimizes the movement time of the last evacuee was constructed to optimize evacuation performance. Solutions to the proposed mathematical model were obtained through an iterative optimization process. The route optimization model was applied to Xidan Station of Beijing Metro Line 4 based on the actual situations, and the calculation results of the model were tested using buildingExodus microscopic evacuation simulation software. The simulation result shows that the proposed model shortens the evacuation time by 16.05%, 3.15% and 2.78% compared with all or none method, equally split method and Logit model, respectively. Furthermore, when the population gets larger, evacuation efficiency in the proposed model has a greater advantage.