A series of VTES/TEOS composite xerogels covalently grafted with a novel complex Ru(phen)2(Dppz-Si)Cl2 were prepared, using the alkoxysilane-modified dipyrido[3,2-a:2′,3′-c]phenazine compound (denoted as Dppz-Si) as the second ligand of the Ru(phen)2Cl2 (phen = 1,10-phenanthroline) complex and a precursor of the sol–gel process. Bulk xerogels were obtained by co-hydrolyzing and co-condensation from a mixture of triethoxysilane (TEOS), Ru(phen)2(Dppz-Si)Cl2 and Vinyltriethoxysilane (VTES). The luminescence intensity of composite xerogels is enhanced by 18.2 times, and the sensitivity is improved from 1.1 to 3.1 by optimizing the molar ratio of VTES to TEOS. The composite xerogel containing 80% VTES in precursor was optimal, exhibiting the maximum luminescence intensity and sensitivity. These results indicate that the complex Ru(phen)2(Dppz-Si)Cl2 is sensitive to oxygen concentration, VTES is a kind of excellent organic modifier and can greatly improved photoluminescent (PL) and oxygen sensing performances.