NiFe films have great applications in magnetoresistance devices. In this paper, the effects of Ta buffer layer thickness,NiFe film thickness, annealing temperature and annealing time on the AMR effect of ultrathin NiFe thin films with thickness less than 20 nm were studied systematically. The results show that with the increase of the thickness of Ta buffer layer,the thickness of NiFe thin film and the annealing temperature,the performance of AMR first increases and then decreases. The optimum conditions fo...