Abstract：The Liaocheng-Lankao fault can be divided into three parts based on an analysis of its geological background. This paper describes the characteristics of geological structure and seismic activity of every part in different geological periods. The results show that there exist obvious mercury and radon anomalies in this area. The anomalies are close to each other, and the widths of the anomaly areas are mostly 90～200 m. All these facts suggest that a buried fault does exist, and the fault is an active fault.