Abstract: The observed facts and the researched results show that the ENSO events in the ocean have two different patterns: the Eastern patern and the Central pattern,and the variat ion of the ENSO has important relations to the Central Pattern Tounderstand the mechanism of the ENSO cycle,based on the SODA data set by the University of Maryland,the evolution characteristics of the subsurface temperature anomaly in the equatorial Pacific of the two pattern ENSO events are analyzed by the case study and the composite method. The results show that,the initial source of the subsurface temperature anomaly in the Eastern pattern ENSO events comes from the western Pacific,and that of the Central patern ENSO events occurs in the central Pacific,then the center of the subsurface temperature anomaly moves upward and eastward along the climate thermocline driven by air sea interaction,and the ENSO events happen when they reach the sea surface of the eastern Pacific.The results also show that,due to the warm and cold phase of the Eastern pattern ENSO events,one phase is the initial field of another,while one phase of ENSO events forms,another phase will follow meantime,thereby the ENSO cycle completes. But the Central pattern ENSO events develop under the weak ENSO state with long time succession,and they disturb the regularity of the ENSO cycle and may cause the break of the ENSO cycle.