Development of an multiple monochromatic X-ray imager based on flat Bragg mirror has been reported, The instrument consists of a pinhole array,a Bragg mirror,and a X-ray CCD camera.An array of approximately 300 pinhole in front of a flat Bragg mirrors projects hundreds of images onto the CCD camera afer reflection off the Bragg mirror,which introduces spectral dispersion along the reflection axis. This spectrometer has a spectral resolution of 50—200 （λ/Δλ） according to the Bragg device and processing technique for systematic reconstruction of quasimonochromatic image.Spatial resolution of 10um is achieved by combining it with pinhole imaging system.Specialism software package have been developed for systematic reconstruction an post date processing,it could restructure an image with flexible spectral bandwidth selection.The article mainly emphasizes the characteristic, optimization design of the spectrometer and the specialized X-ray W/B4C multilayer mirror with depth-graded interplannar spacing centered at 2.5 nm.