KBA microscope is a type of non-symmetrical and non-coaxial grazing incidence imaging system. Its configuration is complex, the adjustment precision is high, so that in practical experiment the imaging performance of KBA microscope is not easy to master. Imaging simulation by using optical design saftwave ZEMAX is made to provide valuable reference for adjustment and imaging analysis. The imaging process of KBA microscope for point source is simulated by using ZEMAX. The depth of focus and depth of field of KBA microscope are about 1 mm and 50 mm respectively. The grazing angle affects the imaging greatly according to the simulation. The upper limit of the spatial resolution of KBA microscope is 3 μm for the detector whose pixel is about 10 μm by simulation. The clear X-ray image of KBA microscope is obtained for the grid target whose period is 20 μm based on XINGGUANG Ⅱ facility, which establishes the base for advanced study of developing grazing imaging system.