Abstract: In this paper,the present spaceborne synthetic aperture radar(SAR) image simulation methods are briefly discussed and a method of spaceborne SAR image simulation with airborne SAR image is proposed.In this method,the simulation principles are investigated,the mathematics model and design flow of geometric,spatial resolution,noise and radiation characteristics are carried out in detail,finally are used in computer simulation.The simulated image indicates a high degree of accuracy and demonstrates that this method is valid.