Rhodamine B (Rh B), a kind of fluorescent dye, was encapsulated into the pores of various mesoporous silica materials through postgrafting method. Small angle X-ray diffraction (XRD), nitrogen adsorption-desorption and Fourier transform infrared (FTIR) spectrometry were used to characterize those composites. After encapsulation, the composites showed significant blue-shift in photoluminescence (PL) spectra. The extent of shift changed upon varying mesoporous silica host. This phenomenon is related to the topological structure of mesopores. For the first time, it was observed that not only the size, but also the structure and the curvature of the mesopores have a great influence on PL properties of the composites, and a possible mechanism was also provided. (C) 2009 Elsevier B.V. All rights reserved.