Abstract: Based on the general laws of the floor damage caused by coal mining, the response relation between the floor rock damage and its electrical resistivity are mainly discussed. Then, the principle and method of the direct current electrical resistivity CT surveying technology are introduced. The survey plan is made according to movement characteristics of mining rock strata in floor, and the dynamic direct-current resistivity CT survey is then applied to predict the damage depth of coal floor. In the return airway of face 1028 in Huaibei Mine, two boreholes were drilled in the coal floor, with a certain number of electrodes buried in the holes, the survey profile was formed between them. With characteristics of electric fields in rock strata in different time measured according to advance of working face, and its electrical resistivity values simulated inversely, the responses of rock strata to electrical resistance during the evolution of fractures were obtained and the damage depth of coal floor in face 1028 was determined to be 17m, which provides visual and effective technical parameters for the coal mining safety. Test results show that direct current electrical resistivity CT technique can detect coal floor mining damage evolution process effectively, and illustrate the floor deformation and damage in the process of mining, which is conducive to the water-inrush forecast, prevention and control.