Abstract: Ta/NiO/NiFe/Ta multilayers were prepared by magnetron sputtering. The composition and chemical states at the interface region of NiO/NiFe were studied using the angle-resolved X-ray photoelectron spectroscopy (XPS). The results show that there are two thermodynamically favorable reactions at NiO/NiFe interface: NiO+Fe = Ni+FeO and 3NiO+2Fe =3 Ni+Fe₂O₃ The thickness of the chemical reaction as estimated by angle-resolved XPS was about 1-1.5 nm. These interface reaction products are magnetic defects, and- the exchange coupling field H_ex and the coercivity H_c of NiO/NiFe are affected by these defects.