By using the ERA-40 monthly mean reanalysis data from 1957 to 2002 and monthly observational SSTs, including global extra tropical, tropical oceans, Indian Ocean-Pacific in tropics, tropical Indian Ocean and tropical Pacific, from 1950 to 2000 as well as the experiments by the NCAR CAM3 as the global atmospheric model, the variations of the east Asian subtropical westerly jet (EAWJ) and its relation with SSTA are analyzed. The results show that EAWJ has the strengthening trend, whose intensity index has a significant period of 3 a from 1957 to 2001. SSTAs from tropical oceans, especially tropical Pacific, have significant impact on the variation of the EAWJ. When the SST from tropical Pacific rises, the EAWJ strengthens.