Abstract
We report the details on the construction, commissioning, and tests of a soft X-ray diffractometer. It has been verified that the sphere errors and angle positioning errors of the difffractometer are withim the designed values given in the specification. The vacuum and soft X-fay photon detection have also been tested and satifsfactory results have been obtained. Some test experiments such as soft X-ray powder diffraction and reflectivity measurements carried out reveal the capability of this diffractometer in characterizing mesoscopic materials structures.