The physical model of real ruled grating is proposed, the corresponding expression of diffraction efficiency is given, and design principle of blazed grating for frequency-selection oscillation in zero-order output for an infrared (IR) laser is introduced. On the base of the result of theory analysis, the technologies are adopted that adjusting the ruled load to control the zero-order plane of the grating and bi-directionally gradually approach the design value of the diffraction efficiencies of the zero-order and first-order, the gilt blazed grating is made with the first-order diffraction efficiency of 86.5% and the zero-order diffraction efficiency of 10.3% in Littrow form. The testing result shows that the deviations of the zero-order and first-order diffraction efficiency from the designed central value are only 0.6% and 3%, respectively.