Abstract: Evacuation ability of building depends on the exit. Proper exit design can improve the efficiency and safety of evacuation. The split-flow wall before exit can not only improve the evacuation efficiency by increasing pedestrian flow rate at exit , but also enhance the security of evacuation by reducing the crowd degree before exit. Based on cellular automaton, a floor field model has been established. Considering the distance to the exit and the crowd distribution before exit, we put forward a reasonable exit-selection model. The conflict function has been introduced to solve the problem of conflict among the evacuees. Flow rate and conflict numbers are assigned as two key parameters to analyze the influence of split-flow wall on evacuation efficiency and safety. Through a lot of evacuation simulation experiments about the influence of the length of split-flow wall and the distance between split-flow wall and exit on evacuation, we find that a split-flow wall with certain length can significantly reduce the numbers of conflict and improve the safety of evacuation; and proper distance between the split-flow wall and exit can improve the evacuation efficiency.