Abstract: The climatological features of large-scale vertically integrated moisture transport(VIMT) in seasonal transition over Asian-Australian monsoon(AAM)regions have been investigated using NCEP/NCAR analysis for the 1957～2001 period.It is shown that the basic features of moisture transport in seasonal transition from winter to summer are establishment of summertime strong transport belt and its eastward expansion accompanying with a series of synoptic and climatological events,such as the activity of Sri Lanka low vortex,the occurrence of strong northward cross-equatorial transport,the eastward retreat of the West Pacific subtropical high(WPSH) and the onset of South China Sea(SCS) summer monsoon,etc.While the main characteristics in seasonal migration from summer to winter are characterized by the westward expansion of easterly moisture transport originating from western pacific along the southern periphery of WPSH.It is also strongly characterized by the breakup and westward retreat of summertime strong transport belt,the formation of Asian low-latitude easterly transport belt,and then occurrence of southward cross-equatorial transport and summer westerly transport over Australian and Southern Indian Ocean.Further analysis shows that associated with evolving annual cycle,the meridional migration features of westerly moisture transport in areas to the east and west of Indochina Peninsular are quite different,which may also denote different forming mechanisms between the Indian monsoon and East Asian-Western Pacific monsoon.