To explore the behaviour of bioelectret film in mineralization and degradation in vitro, chitosan film was prepared and polarized in an electric field at room temperature. Polarized and unpolarized chitosan films were soaked in 1.5 × SBF (simulated body fluid) solutions for 7, 14 and 28 d at 37 ℃. The negativelycharged surface of the bioelectret film promoted greater mineralization than did unpolarized chitosan. Apatite formation on the surface of the films was identified by X- ray diffraction and scanning electron microscopy. Bioelectret films had a higher rate of degradation than unpolarized material in vitro (pH 7.4, 37 ℃ ) in the presence of 1.5mg/mL lysozyme over 7 d. The electret effect facilitated ths degradation of the film. After 14 d, the degradation rates of the two kinds of film were the same.