In order to simulate and predict the airflow of air conditioning ventilation room accurately, the author tries a brand-new model test method. On a special built rig, the author carries out a series of experiments of using the salt liquor diffusion motion in the water to simulate non-isothermal indoor airflow. The author uses PIV to test experiment result and compares CFD result with experiment result. The result shows that the model test agrees well with numerical simulation flow line and their vector field of the velocity accords by and large. It is a feasible model test method.