SAR (synthetic aperture radar) image simulation of the Bund building group in Shanghai was conducted with RaySAR software. The reflectivity maps corresponding to different signal bounce levels and signal bounce level distribution map were plotted. Combined with the geometric and physical information of the targets, the relationship between punctate/linear signatures in simulated SAR image and building structure, different signal bounce level and building structure were analyzed. Seen from the experiment results, the bounce level of radar echo signal was closely related to the structural details of targets. The location and distribution of the Permanent Scatterers (PS) selected by PS InSAR on the real radar image sequences were in good agreement with the double, especially the triple bounce signals in the simulated SAR image. Therefore, the initial precise positioning of PSs on the buildings are realised.