Biot'S porous media theory describes the relationship between dynamic characteriza—tion of seismic waves and reservoir parameters，such as porosity，permeability and viscosity The acoustic modeling method can be applicated to investigate the characteristics ofhydrocarbon reservoirs．Based on Biot's acoustic equation，this pap’er presented a twodi—mensional finitedifference method which involves numerical simulation of lowfreq uence a—coustic wave propaga tion in porous’media．Some problems such as boundary conditions and grid dispersion are discussed．A fluid-filled，layered porous media model is simulatedusing this method，and its synthetic cross well seismograms and time snapshots areshown．