Abstract: The Ninghe earthquake of magnitude 6.9 (1976, Nov. 15) can be regarded as a continuation of the Tangshan earthquake of magnitude 7.8 (1976, July 28). The latter was resulted from the action of the NEE trending compressive stress on the interlockingportion of the NE trending Tangshan fault zone. The seismogenetic structure concerned shows itself as a kind of asymmetric bilateral rupture. A new stress-concentrated area occurred, when the rupture spreads toward south-west and intersected the NW and NWW trending faults in the vicinity of Ninghe. This area under study was once more subjected to fracturing under the action of the NEE trending compressive stress leading to the occurrence of an earthquake of magnitude 6.9.The main fracture plane caused by the Ninghe earthquake still lies within the NE trending Tangshan fault zone inducing the sinistral slip of the NW trending fault. It was, therefore, a consequent of a simultaneous fracturing of the conjugate faults.Comparing and analysing the seismogenetic structure and the fissures, focal mechanism and the characteristics of the aftershock sequences of both the Ninghe and the Tangshan earthquakes it is suggested that the two earthquakes are tectonically related and expressed as main shock-aftershock relationship. This characteristic may serve as a clues to predict the strong aftershocks. It is found that after a main shock the aftershocks were mostly distributed along the trend of the main fracture zone, whereas strong aftershocks usually occurred at the locking portion of a transverse structure.