The effect of corona discharge treatment on biaxially oriented polyethylene terephthalate (BOPET) film was investigated. The BOPET film and corona treated BOPET film were characterized by ATR-FTIR, XPS, SEM and AFM. It was found that many polar functional groups were generated on the surface of corona treated BOPET film and that this surface was etched after corona discharge treatment. Based on the results of the observations and analysis, a mechanism for the corona discharge treatment of BOPET film is proposed and the reactions that occur upon this treatment are put forward in detail.