Abstract:We offer the expression of 3-D Gaussian beam,discuss how to synthesize seismogram by 3-D Gaussian beam,and describe several examples of synthesizing three-component VSP data with the use of geological models.As can be seen in the case of 2-D Gaussian beam method,the seismic wave field obtained by 3-D Gaussian beam method has wave properties in both kinematics and high-frequency dynamics; and rather good effect also can be seen in the singular(or critical)area of asymptotic ray tracing method.What is more,its another outstanding advantage is that only initial value ray tracing is needed,which is particularly important in the case of 3-D medium.