Abstract: The computation of seismic traveltime is important content of ray tracing method,how to calculate the seismic traveltime effectively and increase the computation accuracy are widely concerned.In order to overcome the shortcomings of the traditional ray tracing algorithm(Shooting method of initial value and Bending method of boundary value),A variety of new methods and new technologies have been improved in the past 10 years.With the development of seismic exploration technology,it is necessary to study the computation of seismic traveltime and the methods of ray tracing in threedimensional medium model.Based on the linear traveltime interpolation (LTI) method to calculate twodimensional seismic traveltime,in this article,a method to calculate the threedimensional seismic traveltime is proposed by using bilinear interpolation,and its calculation formula deduced.Through numerical simulation calculation and the contrast with the analytic solution,the correctness of the principle of the method is proved,but also the method proved with a higher computation accuracy.

Key words: ray tracing, seismic traveltime, bilinear interpolation, threedimensional structure, numerical simulation