Abstract: Four types of optical polishing pitches with different contents of pitch and rosin were prepared, and the morphology, penetration, glass transition temperature, softening point and viscosity of these polishing pitches were investigated. Three physical states of the polishing pitches were analyzed based on the composition and structure using glass transition temperature and softening point as the transition temperatures of physical states. It was experimentally found that the polishing pitch with the pitch and rosin mass rate of 30% and 70% could be well applied to large-aperture laser glass. It provides an advantage for controlling the astigmatism and surface defect efficiently. Quantitative studies on physical parameters of optical polishing pitch is beneficial for the preparation, quality inspection and stable performance of optical polishing pitch, and could also improve the polishing efficiency of large-aperture laser glass.