The Yb3＋-doped silica glasses with different Yb3＋ doping concentrations were prepared by the SiCl_4hydrolysis doping and powder melting technology based on the high frequency plas ma.Influence of Yb3＋ doping concentration on physical and optical properties of the Yb3＋-dop ed silica glass is investigated.When Al³⁺ doping concentration is fixed,wi th increasing Yb3＋ doping concen tration gradually,the density and refractive index of the Yb3＋-doped si lica glass are increased,the integral absorption cross section and the spontaneous emission probability are also increased gradually,but the absorption cross section and the fluorescent life are decreased.The laser parameters,such as the minimum particle number of excit ed state,also gradually become bigger.This shows that the cluster effect of Yb3＋ occurs when Yb 3＋/Al³⁺ ratio increases.