Salt water simulation was used to study the movement characteristics of smoke in an atrium building. The flow patterns in an atrium were simulated using a salt water modeling technique. Both the buoyant plume and circulation patterns were observed, and the mechanism of the formation of the circulation was analyzed. Although salt water simulation has been long recognized as one of the most effective means for the study of building fire smoke movement, it has seldom been applied to the study of the behavior of smoke in atria. In an atrium the circulation of smoke within the atrium usually will affect the smoke drainage potential from the atrium. The fire smoke movement in an atrium is much more complicated than that in a single room and a corridor. In an atrium building isolated from ambient air at its bottom, smoke plume circulation often occurs and the smoke evacuation efficiency of this kind of atrium is the poorest.