Abstract: For millimeter wave high resolution application, the paper first analyze the phase error of slant range unwrap, found that the slant range should express to forth item to make sure phase error less than p/4 and adopt CS processing to get signal unwrap before azimuth SPECAN processing. Then study and verify the azimuth SPECAN processing and sector phenomena by simulation and real data, delete sector phenomena by CZT. Sub-aperture imaging and image mosaic test based on real data verify the correctness and feasibility of the proposed method.