Abstract: The numerical simulation model of Air-Modulated Speaker(AMS)by utilizing a finite volume compressible real gas CFD solver and dynamic mesh technique is described. The engineering model takes into account the main geometric characteristics of the AMS and more physical factors compared with the"quasi-steady"theory in input parameter, high frequency response, low subsonic error, working gas model and sound energy conversion mechanism. Different turbulent model, grid density and near wall treatment are employed to predict steady flow of boundary layer separate in acoustic zone, and numerical results are analyzed to choose ideal model parameters. Comparison of simulation results of unsteady flow by setting modulate frequency of 100Hz and changing chamber pressure is made for investigation of sensitivity and understanding of phonation process in detail.The numerical model is convenient to be used in design and performance estimation of high-power acoustic source, and provides a basic tool for capability advance and near field sound prediction.