Abstract: A great amount of newly-collected single-channel seismic profiles have been acquired recently from the Yellow and Bohai Seas. Preliminary interpretation of the seismic data for active faults has been carried out by the authors. Results show that these active faults are inherited from old ones and reactivated in Cenozoic by neotectonics, and occur in cluster into large fault zones. The reactivation of the faults was usually consistent with regional tectonic movements. There are more active faults in the Bohai Sea due to the neotectonic movements related to the activity of the Tancheng-Lujiang fault .