Abstract: The responses of the atmospheric vertical circulations to the anomalies of the sea surface temperatures in the tropical regions are computed numerically with two-level primitive equation model in the tropical regions for two cases: (1) anomalous warming and (2) anomalous cooling. It is shown in our experiments that there is a opposite developing trend between the Walker circulation and Hadley circulation which was discovered by Chinese meteorologists. We have further developed the Bjerknes' hypothesis. It is indicated that the east-west gradient of the ocean temperature in the tropical regions may play a major role in the fomation of the two perpendicularvertical circulations.