polyacrylic acid-polypyrene methyl acrylate copolymer was synthesized via radical polymerization with azobisisobutyronitrile (AIBN). 1H-NMR, FT-IR and UV spectrum were used to determine the structure of polyacrylic acid-polypyrene methyl acrylate copolymer. Dynamic light scattering (DLS) was used to study diameter of the polyacrylic acid-polypyrene methyl acrylate copolymer. The results show that acrylic acid and pyrene methyl acrylate polymerized with AIBN. The molar proportion of acrylic acid and pyrene methyl acrylate in polyacrylic acid-polypyrene methyl acrylate copolymer is 20∶1. Using ultrasound method, the copolymer micelles were prepared by adding dropwise 1 mg/mL copolymer solution in tetrahydrofuran (THF) into 4 mL deionized water. Under the irradiation of ultraviolet light, the copolymer micelles collapsed.