Er-doped silica glasses (5 xlO :t Er/Si mol) were prepared by sol -gel method. Gel samples underwent dehydration in carbon tetrachloride environment. It shows that carbon tetrachloride can remove hydroxyl group effectively, as a result, IV,V1 -IW1 fluorescence lifetime rises quickly. It is also found that fluorescence lifetime is strongly dependent on OH concentration. For samples annealed in carbon tetrachloridt' at 900 fluorescence lifetime as long as 6ms was reached.