Micro-arc oxidation( MAO) coatings on Ti-6Al-4V alloys were fabricated in the electrolyte mixed with( NaPO3)6 and FeSO4 for various concentrations. And the microstructure,phase composition and chemical composition of the coatings were characterized by scanning electron microscope( SEM),X-ray diffraction( XRD) and X-ray photoelectron spectroscopy( XPS). The bonding strength and infrared emissivity in a wavelength range of 5 ～20 μm of the coatings were measured by the tensile test machine and Fourier Transform Infrared( FTIR). The results show that the thickness,roughness and bonding strength of the coatings increase with the addition of FeSO4,thus the infrared emissivity first increases and then decreases.The coating exhibits the highest infrared emissivity value( about 0. 86) when the concentration of FeSO4 is 6 g/L. The elements Fe and P existe as the amorphous state of Fe2O3,H2PO4-,P2O7(4-) in the coatings based on the XRD and XPS results. The Fe doping and disordered structure of the amorphous state are conducive to the generation of local energy levels and the enhancement of polar oscillation between atoms,which promote the increase of the infrared emissivity.