The traditional methods for 3D building extraction from high resolution monoscopic SAR imagery extract the footprint from bright lines caused by double bounce between ground and wall, then estimate height from features such as layover, shadow etc. However, it is very common that bright lines of buildings with large aspect angles are unrecognizable in SAR imagery, which makes these traditional methods useless. A new method was proposed for 3D extraction of these kinds of buildings from a single high resolution amplitude SAR image. This method relies on the constraint of geometrical model, assuming a parallelepipedic 3D building model. The performance of this new method were validated on test SAR data over two urban area.