The imaging characteristics of a Kirkpatrick-Baez (KB) mirror were studied using a home-developed code.The numerical recipe of the code was based on coordinate transformation of ray tracing.The spatial resolution and the field of view were obtained.For given parameters,the properties of the KB mirror imaging were compared to that of a Fresnel zone plate (FZP),and the application range of the two imaging techniques was given.The KB mirror has a relatively high efficiency.Its spatial resolution is 0.71 μm in the centre of the field of view,but decreases to 6 μm as the object position deviates from the field-of-view center by ±200 μm,thus it is suitable for small field-of-view imaging.The FZP can realize a higher spatial resolution up to 0.39 μm and the resolution almost unchanges within ±13 mm field of view,which can be applied to large field-of-view,high-resolution X-ray imaging.imaging.