Abstract: Soft magnetic alloy Ta/Ni_0.65Co_0.35 films, whose magnetostriction coefficient is close to zero, were selected as sensitive layer. The effects of heat treatment on the microstructure and the anisotropie magnetoresistance (AMR) properties of Ta/Ni₆₅Co₃₅ films were investigated. A magnetic resistance element with Barber electrode structure was made and its output characteristics were tested. The results show that vacuum annealing can be effective in reducing the stress and impurity defect distribution in the films, increase the grain size, reduce the scattering of grain boundaries to conduction electrons, and make the AMR value effectively improve. Vacuum magnetic annealing is conducive to raising the films' uniaxial anisotropy and make the AMR value of the films and the sensitivity of the magnetic sensor element increase.