A set of experiments was conducted to study the mechanisms of smoke movement in emergency staircase by varying the height of opened window in a scaled building model with 12 floors. Stack effect and turbulent mixing are found to be primarily responsible for the vertical movement of hot smoke in the emergency staircase. It is found that the velocity of hot smoke movement has two quasi-steady state stages. The turbulent mixing plays a significant role in smoke movement at the first stage while the stack effect becomes dominant at the second stage. The mechanisms of smoke movement have great effects on the vertical temperature distribution in the staircase. Temperature attenuation coefficient beta in the turbulent mixing stage is greater than that in the stack effect stage. Moreover, heat release rate of fire source and height of opened window significantly affect the duration of stage and temperature attenuation coefficient beta. The results could be beneficial for engineers to design the smoke control system in the emergency staircase in high-rise buildings. (C) 2014 Elsevier B.V. All rights reserved.