In order to determine optical constants of azo nickel chelate (Ni(azo)2) thin film, the ellipsometric spectra of Ni(azo)2 thin film, which prepared by spin-coating method on a single-crystal silicon, have been investigated on a scanning ellipsometer with the analyzer and polarizer rotating synchronously. The complex refractive index, complex dielectric function, absorption coefficient and thickness of the film were obtained through drawing up simulation. The absorption spectrum is discussed. These results indicate that the film has a good reflective and absorption characters at the wavelength of 650 nm and is promising for application as recording media for digital versatile disc (DVD-R).