Abstract: A series of 4,3-benzoacridone-1,8-naphthalimide disperse dyes were synthesized with 4-Bromo-1,8-naphthalic anhydride as raw material, through halogenation, imidation, condensation and cyclization. Their structures were identified by elementary analysis,IR, MS and the other methods. Their UV absorption and fluorescence emission spectrum together with malor extinction coeffifients, fluorescence quanrum yields and Stockes' migrations were measured. Their photostability were determined in DMF solutions under light radiation. The results show that these dyes synthesized are quite stable to light and the photochemical reactions are regarded as first order reactions.