Abstract:Anisotropic media mainly show transverse isotropic characteristics,and the transverse isotropic media with dipping symmetric axis have very universal characteristics. The transverse isotropic media are classed into some types first. Then elastic parameters of TI media in common coordinate system are obtained in terms of principle that potential energy is independent of coordinate system,this way is suited to establish relations between elastic parameters in different coordinate systems.Finally,phase velocity analysis and wave field forward modeling in TI medium are achieved on the basis of wave equation in anisotropic medium. The results indicate that medium is anisotropic in vertical plane along seismic line when symmetric axis slants,and that two symmetric axes of wavefront point respectively the dip direction of medium symmetric-axis and its normal direction when seismic line is perpendicular to trend.