Abstract: To validate the capability of interferometric algorithm and give useful complex INSAR data for INSAR study, a new method of INSAR (interferometric SAR) simulation was carried out. As the backscattering coefficient and thermal noise and other factors were concerned, a model of simulation of INSAR based on complex image was deduced; also a new method used to determine the slant distance accurately was analyzed and given. With this method, complex image data for interferometric SAR can be generated fast and effectively, and high-quality phase interferograms without break points can be obtained conveniently. This model can produce data for registration and phase unwrapping, and baseline estimate method can also be validated with the data. The results of simulation on computer show that the new model is capable and accurate; the new method to determine the slant distance is fast and effective.