Abstract: By using the Pacific SST data,we have analysed the SST variations in the western tropical Pacific(WTP) and their relationship with the SST variations in the eastern equatorial Pacific(EEP).The analysis results show that a relation exists between the variations of SST in the WTP and the ENSO activities. The variations of SST anomallies are at the wave trough in the la Nino years and are at the wave ridge in the La Nino years.The results also show that a weak negative correlation relationship exists between the SST variations in the WTP and those in the EEP. The occurrence of SST variatiofis in the WTP appears several months to even about one year prior to that in the EEP.The sub-surface sea temperatures in the warm pool in the western Pacific are analysed. It is found that there exists quasi-biennial oscillation. The raise of sub-surface sea temperatures occurs one year ahead of the occurrence of the E1 Nino event. Nevertheless, the appearance of the positive temperature anomalies. in the warm pool do not always leads to the occurrence of a E1 Nino events. The maximum variations of the sub-surface temperatures appear in the lever batween 50m and 200m. The maximum amplitude is up to 5°C.