Aiming at the problems that there exisited overlap regions between the beams of adjacent feeds in passive milli- meter-wave focal plane array (FPA) and the images are not clear, a focal plane imaging method combined with interferome- try was proposed to generate more image pixels than the conventional FPA imaging methods. By combining coherent and in- coherent technologies, the method can increase the number of image pixels. Therefore, the spatial resolution of passive mil- limeter-wave multi-beams imaging was improved. Both theoretical analysis and simulation results demonstrate the effective- ness of the method.