A comparison of climate records between Chinese Loess Plateau which shows a strengthening of summer monsoon in the last 0.6 Ma and a strengthening of Asia summer monsoon during 35-25 and 4-2.5ka B.P. intervals, and the Australian records which show a strengthening of aridity or desertification suggest that the Australian high leading to the desertification strengthened the Asia summer monsoon in the past through the cross-equator circulation. The synchronous variation in the Holocene Optimum as indicated by Asia and Australia climate records, on the other hand, suggests that the cross-equator East Asia winter monsoon circulation related to the Mongolia high might have influenced the Australia summer monsoon. The interaction of the monsoon climate between southern and northern hemispheres through cross-equator circulation probably started to be obvious since 0.6 Ma B. P. A comparison of climate records between Chinese Loess Plateau which shows a strengthening of summer monsoon in the last 0.6 Ma and a strengthening of Asia summer monsoon during 35-25 and 4-2.5 ka BP intervals, and the Australian records which show a strengthening of aridity or desertification suggest that the Australian high leading to the desertification strengthened the Asia summer monsoon in the past through the cross-equator circulation. The synchronous variation in the Holocene Optimum as indicated by Asia and Australia climate records, on the other hand, suggests that the cross-equator East Asia winter monsoon circulation related to the Mongolia high might have influenced the Australia summer monsoon. The interaction of the monsoon climate between southern and northern hemispheres through cross-equator circulation since started to be obvious since 0.6 Ma BP