Abstract: The pinning effect of the NiO layer was investigated in the NiO 70nm/Co 5.5nm/Cu 3.5nm/Co 5.5nm spin valve by rotating the applying field in this paper. It was found that the pinned direction in the sample is unique. The high magnetoresistance value and high magnetic sensitivity resulted from the pinning effect can be obtained only when the applying field increases along the opposite pinned direction.