The factors effecting on the diffraction efficiencies of blazed gratings were researched and the parameters fabricating the blazed gratings were determined by holographic ion beam etching. On the basis of above, two kinds of blazed gratings with a line density of 1200 lp/mm and blazed wavelength of 250 nm and 330 nm were fabricated, respectively, and then their blazed angles were measured by a Atomic Force Microscopy(AFM) and the diffraction efficiencies were measured by a plane grating diffraction efficiency instrument. Obtained results show that the 250 nm blazed grating with a size of 85 mm×85 mm has a blazed angle of 8.54°and a right angle of 72° and its diffraction efficiency is about 81% at 250 nm. Moreover, the 330 nm blazed grating with a size of 60 mm×60 mm has a blazed angle of 11.68°and a right angle of 74° and its diffraction efficiency is about 80% at 330 nm. These data demonstrate that experimental results are well in agreement with that calculated ones and illustrate that blazed angles can be controlled in grating fabrication process. By using the proposed method, the ultraviolet blazed gratings with diffraction efficiency more than 75% can be fabricated on a large size substrate.