Based on drilling exploration cross faults, this paper presents Depth-Time （D-T） analysis method for compositing drilling section exploration. The method designs D-T graph （ depth as Y axis, time of sediment as X axis） , analyzes the defference of sedimentation speed inboth sides of fault, determines the activity time and displacement of fault. The method is applied in works of urban fault exploration in Fuzhou basin and Quanzhou basin, and brings good results. At last, the influence factors to the method are analyzed, and it is considered the key factor is flatness of terrain （ ancient terrain） of the drilling site.