The time decay curves of fluorescence intensity of acetic acid-water solution induced by the exciting light with wavelength of 284 nm in different volume percentages are studied,and the decay processes of fluorescence intensity are detected at the emission peak of 334 nm induced by the exciting light with different wavelengths experimentally.It is fitted by an exponential function and the analyzed data is obtained by deconvolution.Through theoretical analysis,the variation of linear dimer(LD) molecular association is analyzed in acetic acid-water solution.Both the relative concentration and the relative fluorescence intensity of different components in acetic acid-water solution are calculated,respectively.The resluts show that the fluorescence lifetime at the acetic acid volume percentage of 80% with the exciting light wavelength of 284 nm is 10.02 ns,related to the maximum volume percentage of LD association structure.The lifetime values of the the emission peaks induced by the exciting light of 304 nm and 316 nm are 8.00 ns and 6.64 ns,respectively.The fluorescence intensity is more sensitive to the exciting light wavelength.The research contributes to the study of the molecular structure characteristics of acetic acid-water polymerization.