Abstract: Using the NCEP/NCAR reanalysis data during 1980－2004, The authors choose the strong and weak extrema of cross-equatorial flow (CEF) during May to August as typical samples, and then analyze the circulation configuration of strong/weak CEF to the north of Australia. The results show that the strong CEF always corresponds to the strong convergence zone in the Northern Hemisphere, or strong Australia high in the Southern Hemisphere, or frequent Australian cold air activities, and it also corresponds to the circulation situation that the location of the western Pacific subtropical high (WPSH) is more eastward or northward than normal; the weak CEF always corresponds to the circulation situation that the location of the WPSH is more westward or southward than normal, or the frequent occurrence of conjunct evolution processes of the WPSH and the convergence zone.