A method of laser speckle for information marks measurement of optical disk was proposed.When laser beam illuminating the weak scattering objectted,there was an approximately linear relationship between the speckle average contrast and the roughness of the illuminated surface in the diffraction field.According to this theory,the optical disk can be regarded as a weak diffuse object. In this paper,the patterns generated by several regions of blank,read-in-data and damaged optical disks were studied. The experimental results indicated that this method could be applied to obtain some statistical characteristics of optical disk due to its advantages of quantitative and full-field measurement,which provided a novel technique to character the optical disk quality.