Abstract: The circulation differences between more and less rainfall period in annually first rainy season of Guangxi in decadal scale and its association with sea surface temperature of the Indian Ocean in Southern Hemisphere are investigated by using the NCEP/NCAR reanalysis data.The results show as follows.The uniform change pattern of annually first rainy season precipitation of Guangxi shows a 20-year decadal oscillation and a 3-year interannual change.On the other hand,the pattern with out-of-phase change between the north and the south regions of Guangxi has a 6-year interannual periodicity and quasi-biennial oscillation.In the period of more precipitation,the surface temperature in Eurasia is positively anomalous that leads to stronger low-pressure systems on land and larger thermal contrast between land and ocean.Therefore,the instability of air column and upward flow over Guangxi are intensified while the Hadley cell is weakened.Furthermore,the weaker Western Pacific Ocean subtropical High and South Asia High,together with a stronger cross-equatorial flow,result in more humidity transportation and rainfall.The correlation analysis indicates that sea surface temperature of the Indian Ocean in Southern Hemisphere is closely associated with the variation of the annually first rainy season precipitation of Guangxi on decadal scale by influencing the south-east Asian monsoon through the cross-equatorial flow.