Seismic reflection exploration is the main technique in present urban active faults detecting.The effect of investigating fault and its up-breakpoint in thick Quaternary sediments depends on the working methods and technical parameters.Qiaobei-Suqian fault is an important buried fault along Tan-Lu fault zone in Jiangsu. In this paper,based on QL14 line laid on the fault in thick sediments during the active fault survey in Suqian City and aimed at investigating the spatial distribution,characteristics and activities of the fault controlled by the line,the authors used different seismic exploration methods and acquisition parameters to perform a high-resolution seismic reflection experiment and obtain the imaging of buried fault in the light of the work thinking of combination and fractional steps and according to different targets,the depth of the target layer and the accuracy requirement.The technique solved the contradiction between the field data acquisition and the geological task.The authors obtained high-resolution images of structures in the depths of 16~450 m after data processing,and the prospecting results provide seismological evidence for the position layout of composite drilling sections,the depth designing of drilling and the evaluation of fault activity.The high-precision composite drilling geological sections show that the main stratigraphic boundaries and tectonic features obtained from the seismic exploration methods are quite consistent with the results from the composite drilling geological section.The experimental result shows that the combined detection methods can receive the attitude and distribution of the fault in different depths and the complete distribution image from the depth to the shallow part of the fault.The feasibility of the seismic exploration methods for locating the buried fault and determining its activity in thick Quaternary sediments and the efficiency of the combination of seismic exploration and composite drilling geological profiles are also demonstrated in this study.