The interannual relationships and its interdecadal variabilities between the intensity of summer 850hPa cross-equatorial flows in the Eastern Hemisphere and ENSO are analyzed by using NCEP/NCAR reanalysis data and the sea surface temperatures data of Hadley Center.Results show that Mascarene High was weaker(stronger) and Australia High stronger(weaker) than normal in the El Nino(La Nina) years,which caused summer 850hPa Somali jet was weaker(stronger) and the cross-equatorial flows of about 90°E,105°E,125°E and 150°E were stronger(weaker) than normal.The interannual relationship between Somali jet and ENSO was weakened in the late 1970s while the interannual relationships between the cross-equatorial flows of about 105°E,125°E and 150°E and ENSO were enhanced in the late 1960s.