Antimony-Bismuth alloy is a new functional material for optical super-resolution. It is very important to understand its fundamental optical properties for its applications in optical memory and other photonic devices. Antimony-bismuth alloy films: Sb1-XBiX (X=0, 0.1, 0.2, 0.3, 0.88, 1) are prepared by magnetron sputtering method. Optical constants (refractive index nand extinction coefficient k) of these films are measured by spectroscopic ellipsometer. Results indicate that both refractive index n and extinction coefficient k of the SbBialloy films decrease with rising concentration of bismuth in the visible wavelength range. The refractive index n of SbBi alloy films increase with increasing wavelength, showing the films possessed anomalous dispersion characteristics. The effects of bismuth composition on the surface morphology and microstructure of the films are studied by atomic force microscope and X-ray diffraction analysis respectively. The SbBi alloy films are at polycrystalline states and its crystallization extent increases with rising concentration of bismuth. This may be the major factor influencing its optical constants.