Abstract: A fast wave field simulation algorithm is proposed based on Kirchhoff approximation. Reflected seismic wave field can be computed given that the velocity of underground medium, the spatial position of reflection interface, and the reflectivity are known. The computation efficiency and accuracy are discussed. Aiming at the problem of great computation cost in 3D seismic wave field simulation based on Kirchhoff approximation, we have used two-scale grid units and limited the numerical integral area on interfaces to improve the efficiency and save memory without lowering the accuracy. Numerical examples demonstrate the effectiveness of the algorithm.