Abstract: Itis found in this paper that althongh the South China Sea cyclones and the Bay of Bengal cyclones present some statistical independence, the latter can rest raint the former in intensity and advancing direction. Generally speaking,there is a phase difference of 2-5 days in the pressure fields of the two areas, which rarely develop simultaneously, with a high versus low feature. If cyclones of the two origins happen to take place at the same time,the one in the South China Sea would be prevented from becoming a severe typhoon (V>25m/s) and moves in the same NW direction as the former does.Next, comparison between depressions in the two areas is made in terms of structure characteristics, firstly from their composite fields of low pressure. The main difference is revealed to be the southwestward inclination for depression over the Bay of Bengal and southeastward inclination for that over the South China Sea, a fact resulting from different distribution of their meridional winds. Additionally, the paper points out that the cold core structure is seen in depressions in both areas, suggesting that it mark on of the cyclonic development stages. Finally, the ne-arly consistent meridional winds and their distribution and southwestward-inclined spatial structure characterize both depressions that occur during the same period. It follows that, being subject to greater topographic infiuence, depression in the Bay of Bengal has a somewhat fixed structure while that in the South China Sea can have two, possessing the same features as the former does if they occur at the same time.