There happened two subsiding moments to Bohai Sea in the Cenozoic. The activity of the faults in this area played an important role in affecting the evolution and development of the Bohai basin. Based on seismic data collected in this area, this paper studied the activity of the faults in the southern part of Bohai Sea since the late Pleistocene. The results show that the fault activity is intensive since the late Pleistocene, of which the activity of Tanlu Fault Zone is the most intensive, with the average rate to the vertical slip exceeding 0.06 mm/a. There are two actively tectonic periods, 60 ka B.P. to 53 ka B.P. and 22 ka B.P. to 10 ka B.P., respectively. The faults are possible to induce minor and moderate earthquakes, but hardly the strong ones in recent years.