Anisotropy is widespread in subsurface.The rapid development of PC-Cluster and field seismic acquisition makes it possible to take anisotropic medium into accounted.Scalar wave equation and its RTM,based on acoustic approximation,has becoame a hot issue of the industry.It can overcome the complexity of elastic modeling and computational limitations.In this paper,the authors derived the scalar acoustic equation on the basis of elastic wave theory in anisotropic medium.According to this equation,the authors put forward a reverse time migration strategy.The numerical simulation shows that the scalar wave equations in this paper can better suppress shear wave interference.RTM result of Hess model demonstrates the feasibility when it is used to RTM.