The characteristics of high-order Bragg waveguide grating based on phase-mask method are investigated, and the resonant wavelengths of Bragg waveguide grating with different orders all increase with the increasing of saturation coefficient. Influences of the order of grating, diffraction efficiency of phase mask and saturation coefficient on the refractive index modulation of Bragg waveguide grating are taken into consideration synthetically. The largest refractive index modulation amplitude can be acquired when the order of Bragg waveguide grating is 2 and the saturation coefficient is 0.67. In this case, the maximum reflection and the zero bandwidth of Bragg waveguide grating can reach the maximum. The maximum reflection increases and the zero bandwidth decreases with the increasing of grating length. The saturation coefficient of waveguide grating increases with the product of the writing beam intensity and the writing time. The saturation coefficient is 0.67 when the product is equal to 160 s·W/cm2. The optimal saturation coefficient can be acquired by controlling the writing beam intensity and the writing time.