The optical properties of monolayer GeSb 2Te 4 thin film prepared by vacuum RF sputtering method at the region 400～830 nm were studied. A comparatively large absorption was observed in the wavelength range of 400～600 nm. The optical storage characteristics of GeSb 2Te 4 thin film indicated that larger reflectivity contrast can be obtained at lower writing power Argon laser (514.5 nm) . The erasing reflectivity contrast is low, but it can be improved by multi layer films match.