Abstract: The exchange fields of NiO/NiFe bilayer have been investigated, and the NiO film is deposited by dc magnetron reactive sputtering.It has been shown that exchange field is relation to the ratio of Ar/O₂ (Volume ration), total sputtering pressure and the roughness of substrate.The Ni and O ion in NiO_x is analyzed by means of XPS.The spin-vavie Ta/NiO/NiFe/Cu/NiFe/Ta pinned by NiO is deposited, and its magne-toresistance reaches 2.2% and pinning field is 10.48 KA/m.