It is very import to design an evacuation plan before the emergency occurs in a building. The traditional evacuation plan only provides the fixed escape routes, if an emergency occurs at the different location, the escape route could not be an optimal escape path, people might choose the same exit to escape, it would increase the duration of the escaping time. In this thesis, we propose a method, called “Optimal Escape Route (OER),” OER is according to the locations of people to from groups, and design an optimal escape path for each group. The OER can efficiently decrease the duration of escape time, and let people safely escape from an emergent environment.