This paper mainly describes that nano-scale surface structure change in dangling bond density related to free volume caused the reinforcement of inorganic glass irradiated by electron beam. Based on the results of electron spin resonance experiments, EB irradiation enhanced the density of dangling bonds at the glass surface. To confirm the strengthening principle, we have employed EB irradiation of inorganic glass. The EB reinforcement was explained as caused by stress relaxation induced by dangling bonds formation in the tight network structure of silica and soda glasses.