The abnormal blu e oxide films occurred at the heat-affected zone of zircalloy-4cladding tube af ter electron beam welding,were studied using XPS,EDX,TEM.The resu lts indica te that iron and tin in the a bnormal oxide film exist in the form o f Fe 2 O 3 ,SnO 2 ,and the ratio of Fe to Sn in abnormal blue oxid e film is higher than that of the norma l one.These results will provide the basis of the further researc h.