Abstract: The application of X-ray CT technology to rock damagemeasurement becomes an important part of rock damage mechanics. In this paper,first, the measurement principle, technical specifications anddevelopment of the CT machine are described. Secondly, the application of CT technology to rockdamage measurement are reviewed. Thirdly, the existing methods of CT analysis,including the statistical frequency method put forward by the author,are discussed.Fourthly, all kinds of damage variables based on mean CT values areanalyzed. Finally, the existing problems and future development are pointed out.