Abstract: The variability inter-decadal and inter-annuales of the SST in tropical Pacific in the last 100 years have been found by using the wavelet trans form. It has been also found that the inter-decadal scale period which is considered as the background filed had been changed obviously while the SST in tropical Pacific was increasing clearly and more and more ENSO events are occurring from 1950s. The characters of inter-decadal variability and inter-annual variability have been studied too.