Tb3+ ions and SnO2 nanocrystals (NCs) codoped silica films are fabricated by a soft chemistry-based approach. Via precise adjustment of Sn amounts in precursors, the size and number density of SnO2 NCs can be well controlled by a restrictive crystallization process. The characteristic emission intensity of Tb3+ ions at 541 nm can be greatly enhanced by two orders of magnitude if sensitized by SnO2 NCs with optimized size and number density. Photoluminescence excitation spectra of the films containing different Sn amounts indicate the non-radiative energy transfer process that takes place between Tb3+ ions and surface of SnO2 NCs. The photoluminescence intensity decay curves suggest two kinds of possible occurrence states of Tb3+ ions in codoped samples. All these results suggest the SnO2 NCs represent ideal sensitizers to effectively promote photoluminescence efficiency of Tb3+ ions. Particularly, the soft chemistry-based method reported here is very flexible for the fabrication of rare earth ions doped amorphous thin films, permitting the precise control of size and number density of NCs as sensitizers. We anticipate this fabrication strategy greatly enriches the techniques for the preparation of thin films, providing great promise for the realization of on-chip integration of silica-based optical lasers and amplifiers. (C) 2018 Elsevier B.V. All rights reserved.