According to the difficult problem of evacuations outside the large public places in city fire accidents, considering the impact of urban fire emergency evacuation on the basis of factors, analyze the fire emergency evacuation model. And taking as some gymnasium nearby situation as example, use Dijkstra algorithm and interval number network algorithm to comprehensively optimize factors that affect the transportation network. Acquire the shortest path and minimum danger path. The result shows that the application of model can realize the visualization of fire emergency evacuation path in 3D scene and provide decision support for fire accident emergency evacuation.