Abstract: The Ni₈₁Fe₁₉/Ta films with different Nine thicknesses were.prepared at different base pressures and sputtering pressures. The results of magnetic measurement and atomic force microscope (AFM)showed that the thicker films and the films prepared at the higher base vacuum and the lower sputtering pressure had the larger △R/R. The reason is that the higher base vacuum and the lower sputtering pressure introduce the larger grain-size and the lower surface roughness, which will weaken the scattering of the electrons, reduce the resistance R, and increase the △R/R.In the thicker films, the effect of the larger gum-she will offset that of the larger surface roughness, and the △R/R can be increased.