A form of The 3D model of commercial complex is established by using Building Information Modeling(BIM) technology and transformed into fire dynamic calculation model. The interaction process between high pressure water mist and flame in Superfast fire of large space complex is analyzed. The interaction process between water mist and flame under different injection speed, atomization angle and water mist pressure was studied. Analysis of fire control efficiency of fine water mist. The results show that the atomization Angle increases to a certain extent, and the fire control efficiency of fine water mist improves. The turbulence caused by the large space complex at the early stage of high pressure water mist at different atomization angles is more severe than that in the limited space and the temperature rally. The optimal atomization Angle is greater than the restricted space. The jet velocity increased by a certain amount, the cooling rate and amplitude both increased, The temperature oscillation amplitude and time region are small in the full development stage. As the pressure rises to the critical pressure, the fluctuation after the temperature rises is small, and the better the control effect on the fire source is, when the critical value is exceeded, the flame expands laterally and accelerates the CO flow in the high-temperature flue gas.