Aluminium doping TaNx thin films were deposited on Al2O3 ceramic wafers by DC reactive magnetron sputtering. The influences of nitrogen partial flux on the phase structures and the electrical properties of the samples were investigated in detail. The results show that the main phases in the samples are gradually changed from poor nitrogen phases to rich nitrogen phases with the increase of the nitrogen partial flux. The deposition rate of the samples is decreased with the increase of the nitrogen partial flux. With the increase of the nitrogen partial flux, the resistivity and the absolute value of the temperature coefficient of resistance (TCR) of the samples increase slowly at lower nitrogen partial flux, and then increase remarkably at higher nitrogen partial flux. These experimental results can be explained by the presentation of rich nitrogen phases with higher resistivity and absolute value of the TCR when the samples were prepared at higher nitrogen partial flux.