The niobium oxide coatings with various process parameters were prepared on AZ31 magnesium alloy using DC reactive sputtering technology to reveal the influence of sputtering deposition parameters on the corrosion resistance of niobium oxide coatings. Microstructure and corrosion resistance of the layer were tested with SEM and electrochemical workstations. The results showed that the effects of oxygen flow rate on the microstructure of the coating were not significant, while the corrosion resistance of the layer decreased with the increase in oxygen flow rate. When the sputtering power increased from 60 W to 100 W, the density of the coating surface gradually decreased, even with cracks appearing on the coating surface, and the corrosion resistance first increased and then decreased. As the deposition time increased from 180 min to 420 min, the coating exhibited increased thickness, reduced density, and a corrosion protection effect that first enhanced and then weakened.