Abstract: GAEvac is an evacuation computer model on the basis of geometric method and intellectualized aim distinguishing. This model can express the space of buildings and the body of evacuees through some simple geometry elements;it can also simulate the velocity change of evacuees through collision detection and position adjustment algorithms. By setting target classification and condition decision rules, the choice of evacuation route can be simulated and the group effects can be reflected. To analyze the accuracy of GAEvac, two experiments with different velocity changes and route choices were simulated and the results were compared. Finally, an illustration was made, which shows that this model is of practicability and referring value.