Firstly the role and structure of the sagittally focusing double-crystal monochromator are introduced briefly. Dimensions of the diffraction crystal are determined according to the design requirement. Different kinds of distortions of the diffraction crystal subject to high heat load from synchrotron radiation beam are analyzed. Direct water-cooling is adopted to release the high heat load. The grooved crystal and the cooling structure are designed. Then material choice

orientating and cutting

and grooving of the diffraction crystal are completed in succession. At last the directly water-cooled diffraction crystal applicable for the sagittally focusing double-crystal monochromator is produced which can bear heat load stand of more than 0.5W/mm2.