A photochromic switching copolymer was synthesized by typical radical copolymerization of 2-(9H-carbazol-9-yl) ethyl methacrylate,a vinyl monomer having a spironaphthoxazine residue.It reversibly changed the fluorescent intensity by alterative irradiation with ultraviolet and visible light probably due to the photoinduced electron transfer (PET) between carbazoles and the open form of spirooxazine moiety.By the observation of photoresponsive viscosity and conductance changes,it was confirmed that the copolymer can exhibit excellent viscosity and conductivity switching behaviors.This photoregulated multi-switching behaviors can be potentially applied in all-photon mode optical storage,logic gate and the other molecular devices.