Titanium nitride coatings were prepared on Ti6Al4V titanium alloy via DC reactive sputtering technology at different nitrogen flow rates. The coating was characterized by scanning electron microscope (SEM), X-ray diffractometer (XRD), X-ray photoelectron spectroscopy (XPS), scratch tester, and electrochemical workstation to investigate the influence of nitrogen flow rate on the coating’s microstructure and properties. Results indicate?that at 0.3 mL/min nitrogen flow rate, the coating exhibits an amorphous structure, while at 0.5~3.5 mL/min, there is a titanium nitrogen oxide crystal phase. As the nitrogen flow rate increases, the N element content in the coating decreases, the O element content increases, the coating thickness decreases, and the density, interface bonding, and corrosion resistance are enhanced.