Grazing incidence optics (GIO) is the most important compound in an x-ray detection system; it is used to concentrate the x-ray photons from outer space. A nested planar GIO for x-ray concentration is designed and developed by authors in this paper; planar segments are used as the reflection mirror instead of curved segments because of the simple process and low cost. After the complex assembling process with a special metal supporter, a final circle light spot of phi 12 mm was obtained in the visible light testing experiment of GIO; the effective area of 1710.51 mm(2)@ 1 keV and 530 mm2@ 8 keV is obtained in the x-ray testing experiment with the GIO-SDD combination, which is supposed to be a concentrating detector in xray detection systems.