Based on the actual construction design project and the human distribution in some large supermarkets, two improved design projects are presented because the evacuation staircase width of the fire zones are not distributed symmetrically. One is the improvement to current fire zone design, making the distribution of evacuation staircase width more symmetrically by setting shared evacuation staircase. The other is to relocate the related fire zone, decrease the area of current fire zones and add one more fire zone. The occupant evacuation times of three evacuation scenarios are simulated by EVACNET4. Results show that when the fire zone area is large, to symmetrically distribute the evacuation staircase width of the fire zones is more effective for evacuation. Setting shared evacuation staircase will help for evacuation and improve the efficiency of using the staircase. Decreasing the fire zone area will shorten the evacuation distance, and the evacuation time will be reduced.