In order to capture X-ray selfemission images with spectral and spatial resolution simultaneously from Z-pinch plasmas, an X-ray spectrograph with spherical bent mica crystal was set up. A geometric model was presented to describe the line broadening due to source size in the dispersion plane. The spectral resolution from this model which was consistent with that from ray tracing calculations showed that the best spectral resolution could be obtained when the detector was placed on the Rowland circle. X-ray spectrograph from aluminum wire array Zpinch implosion was recorded on “QiangGuang-I”generator, which indicated spectral resolution of better than 1 000.