Abstract: In order to study the evacuation behavior in a fire, a study on the moving behavior of the people walking upstairs in the smoke environment in residential buildings was conducted.Three different visibility conditions e.g. no smoke, light density of the smoke and dense smoke were set. The research results show that when the people walking in the smoky environment,besides the walking distance, the psychological effect is also an important factor for the movement speed. The light smoke environment has little effect on the moving speed of people. In the thick smoky environment with lower visibility, the people would be panic, and would walk faster with the help of the handrail.The upward moving speed is greater than those in the smokeless and light smoky environments.

Key words: smoky environment, stair, walking upstairs, evacuation, moving speed