Metal-organic framework composites RhB/MOF-5 have been successfully prepared by diffusion of solvent method for the first time. The investigations of LM, XRD, FT-IR, UV-Vis, and photoluminescence confirm the existence of RhB in the pores of MOF-5. The composites which show strong fluorescence and obvious red-shift compared with RhB in CHCl3 could be candidates for applications in optics, especially in laser systems.