When the NNE trending Tan-Lu fault zone passes through the central Bohai Sea, it manifests as several discontinuous faults in the plane view. Data of seismic reflection and drilling revealed great differences of sediment thickness on the both sides of each fault, indicating normal faulting with large amplitudes in a subsiding tectonic setting since the Neogene. These faults constituted boundaries between depressions and uplifts in the central Bohai Sea. In the vertical profiles, these faults had flexure and tilting of some degrees, extending downward to 10~12 km depth. In the shallow portion of the crust above this depth, there was no direct evidence such as horizontal displacements and characteristic deformation showing strike-slip of the Tan-Lu fault zone as previous studies suggested. The strike-slip faulting inferred from focal mechanisms of earthquakes represented the deformation and stress state at depth, which existed together with the residual extensional stress in the shallow crust. Based on analysis of fracture mechanics, it was suggested that the large number of small fractures, which were roughly EW striking in the upper Neogene System of the Bohai Sea, were likely generated by the recent tectonic stress field. They might not be related with the Tan-Lu fault zone or other old faults in the basement in an inheritance or derivative manner.