Interpretation of SAR image in urban area is far from solved with the increase of spatial resolution, and building extraction in SAR image has remained as a tough work. Typically, the outlines of buildings are usually not complete, and the geometric distortions further complicate the appearances of buildings in high resolution SAR images. Thus, in this paper, a strategy based on dual-aspect high resolution SAR images was proposed to extract complete footprint of buildings in urban area. Experiments prove that dual-aspect SAR images, especially with high resolution, are very useful for building extraction in urban areas.