Aiming at decision-making for correct evacuation route and considering real-time effect of indoor fire spread, a shortest route selection model is proposed on the basis of improved ant colony algorithm.Hexagonal grid map is employed to make sure of a constant time spent moving to adjacent grids each time, so the spread of fire and evacuation can be accomplished at the same time.Parameters of fire spread are obtained by using the fire dynamics simulator(FDS).Then the real-time effect of fire spreading on the evacuation route in the process of evacuation is analyzed.Simulated calculations under different circumstances illustrate that the proposed model can solve the problem of “moving diagonally through the wall” and improve the accuracy and efficiency of evacuation, thus serving as guidance for the research on intelligent emergency evacuation system.