Abstract: The interaction of poly (methyl methacrylate) and its copolymer of methyl methacrylic acid with Rh6G in mixed solvent of ethyl acetate and ethyl alcohol with various proportions was studied. It was found that there did not exist any specific interaction between poly(methyl methacrylate) and Rh6G in all mixed solvent used. The case of copolymer was quite different. By addition of Rh6G the specific viscosity of copolymer in solvent of low alcohol content was enhanced and the polyelectrolyte effect of copolymer in solvent of high alcohol content was suppressed. The fluorescence intensity of Rh6G was decreased in presence of copolymer, especially in solvent of high alcohol content. All these experimental facts demonstrated there was interaction between copolymer and Rh6G. It was supposed the interaction was fulfilled through hydrogen bonding between Rh6G molecule and —COOH in low polar solvent and through electrostatic attraction mainly between the quaternary ammonium ion of Rh6G and —COO~- in high polar solvent.