7-hydroxy-4-trifluoromethylcoumarin (7-coumarin) incorporated in mesoporous AlPO4 glass is prepared with dipping method. The effects of 7-Coumarin concentration and pore size of AlPO4 glass on the optical properties and molecular formation of 7-Coumarin are studied by excitation spectra and emission spectra. The main excitation band placed at 372 nm is ascribed to monomeric 7-Coumarin in excitation spectra, and the blue shift of main excitation band is due to the aggregating of fluorescent dimers in the mesoporous glass as 7-Coumarin concentration increases from 1×10-6 mol/L to 1×10-2 mol/L. Red shift of emission band from 421 nm to 435 nm is observed in emission spectra as 7-Coumarin concentration increases from 1×10-6 mol/L to 1×10-2 mol/L. The emission spectra and excitation spectra of two different mesoporous AlPO4 glass with the loading dyes concentration 1.0×10-4 mol/L are studied to investigate the effects of pore size on the optical properties. The blue shift of excitation band from 370 nm to 365 nm, as well as red shift of emission band from 428 nm to 433 nm are observed as the pore diameter of the AlPO4 glass increased from 3.52 nm to 6.74 nm, which reveals less aggregates as H-dimers in the AlPO4 mesoporous glass with smaller pore diameter and that can benefit for loading the dyes in high concentration.