Volume Bragg grating with the grating period 2.1 μm was recorded in the photo-thermo-refractive glass with laser amplitude-split interference and "two-step" heat treatment process. The diffraction efficiency and angular selectivity of Bragg grating are very much affected by the laser dosage. The He-Cd laser with UV wavelength 325 nm is used. With the increase of UV dosage, the diffraction efficiency increases constantly. When the UV dosage increases to 0.6 J/m2, the diffraction efficiency of the grating reaches the maximum value of 80.02%., The efficiency will decrease as the UV dosage increases more than 0.6 J/m2 and remain a stable value as the dosage reaches at 1.5 J/m2, while the grating absorption change is less than 5%. The grating angle selectivity remains stable as the dosage changes. The experiment results show that the increase of UV dosage enhances the silver containing particles absorption at work wavelength 532 nm. The transmitted diffraction light was attenuated and the diffraction efficiency decreased.