Abstract: PDC bit can make some difficulties in geological logging because of it's fast rate of drilling, the fine cuttings and the small change of the drilling time. So it is necessary to find more effective method to distinguish the lithology. The geological logging in Xihu Trough makes it clear that the lithology has close relation to the curve change of torque and the rate of top drive, and it is important to apply these logging parameters in order to establish the lithology section fast, to discover the oil and gas layer in time and to fix the cored layer exactly.