High-temperature sterilization is applied when film-laminated steel is used as food-can packaging material. To study the effect of this sterilization on the barrier property of biaxially oriented polyester(BOPET)film, the water vapor transmission, thermal properties, and microstructure of BOPET that had undergone different sterilization time were analyzed. Results show that water vapor transmission is decreased by sterilization, and that with increased sterilization treatment time, the melting point and melting enthalpy of BOPET increases. Moreover,the microstructure of BOPET film also can be improved by sterilization, in which the quantity of crystal nuclei and the crystallization density increase to form a network-like structure,which is beneficial to the barrier property of BOPET film. High-temperature sterilization is applied when the film-laminated steel is used as food-can packaging material. To study the effect of this sterilization on biaxially oriented polyester (BOPET) film, the water vapor transmission, thermal properties, and microstructure of BOPET that had undergone different sterilization time were analyzed. Results show that water vapor transmission is decreased by sterilization, and that with increased sterilization treatment time, the melting point and melting enthalpy of BOPET increases. Moreover, the microstructure of BOPET film also can be improved by sterilization, in which the quantity of crystal nuclei and the crystallization density increase to form a network-like structure, which is beneficial to the barrier property of BOPET film.