In response to regulatory requirements for safety evacuation in metro station, based on the location of emergency, this paper summarizes evacuation path and evacuation volume under different conditions. Discussing the method to calculating evacuation time which is in the code for safety evacuation, the view that safety evacuation simulation should be conducted is proposed. And the four key factors affecting the safety evacuation time in design stage are identified in this paper, mainly including evacuation volume, capacity of evacuation facilities, lifting height from the platform to the concourse or other safety zone, and distribution of evacuation facilities on the platform. By comparing the impact of escalator which is in the opposite direction on evacuation capacity, the rationality of using reverse escalator under the emergency evacuation condition are discussed. Considering on practical work experience, it is suggested that the timing of safety evacuation simulation should be advanced to the preliminary design stage.