Abstract：Firstly，cracks located in the CT images scanned at the stages of stress changing from 20.59 MPa to 31.03 MPa are obtained from the images by means of CT data about sandstone under the uniaxial compression condition. The filter designed in the paper is used to pick up cracks，in which the threshold value is determined after sensitivity analysis. Based on these binary images of crack under each loading step condition，the fractal dimension of area and length of the crack in the sandstone are computed by the methods of yardstick，box-counting，island and sandbox. Finally，the relation between the fractal dimension of crack and the loading process is analyzed，and the fractal feature on the damage and fracture of sandstone is discussed through the evolution information of the fractal dimension.
