This thesis takes smoking room as research object. Based on the combination of CFD simulation and the stepping motor experiment, this paper carries out numerical simulation of the smoke diffusion in the smoking room. The model is verified by PIV experiment, and the relative error is less than 25%. In the end,the indoor smoke velocity and CO mass fraction distribution under different ventilation modes, different smoke source quantities, and different fresh air velocity were obtained. Results showed that the upper side exhaustion is a manner of purifying the indoor smoking effectively. The indoor smoke concentration in different heights is mainly decided by exhaust manners and pollution source location. To increase the smoke source quantity will enhance the indoor air convection, and accelerate the airflow speed with relatively high indoor smoke concentration. The smokers will suffer much more damage from the second hand smoking. To accelerate the speed of new ventilation system is an effective method to decrease the indoor smoking concentration.