Tb-doped luminescent SiO2 xerogel was prepared by the sol-gel technique. FTIR was used to measure the microstructure of the luminescent materials. The luminescence properties were characterized by F-7000 UV-visible fluorescence spectrophotometer. The effects of the molar ratio of H2O on the fluorescence and phosphorescence intensity and phosphorescence lifetime of the sample were mainly investigated. The results showed that for the Tb3+ doped xerogels, the sample of 1∶4∶4 annealed at 650 ℃ reaches the maximum intensity, the sample of 1∶4∶5 annealed at 750 ℃ reaches the maximum, the sample of 1∶4∶6 annealed at 850 ℃ is the strongest. With increasing the amount of water, the luminous intensity of the samples annealed at 750 ℃ was first weakened, then enhanced and finally weakened. It was shown that the luminous intensity of samples is related to the molar ratio of aqueous solutions and annealing temperature, whose influence on the luminous intensity formed a competitive mechanism. Phosphorescence was observed at the same time, illustrating the existence of defects in the matrix space, and that the influence of water on the intensity is the same as that of fluorescence. In addition, with the increase in the molar ratio of aqueous solutions, the amount of defect gradually changed and resulted in a change in the luminescence decay time.