The thermal oxidation process of PVFc was investigated in detail by means of XPS in combination with XRD and XFS.The study of XPS indicated obvious increase in the oxidation state of iron after the thermal oxidation and the intensity change of the Fe 2p_3/2 spectra showed that some intermediate stages occurred during the oxidation of film surface.XFS analysis demonstrated that the content of iron remained unchanged which proved that the above mentioned change occurred only on a very thin surface layer.It was shown from the XPS investigation that the obvious oxidation of iron began at 17O-180℃ and the XRD result showed that the early stage of oxidation did not produce crystalline a-Fe₂O₃ until the oxidation temperature had reached about 380℃.