Abstract: The cross-equatorial flow that comes from the Northern Hemisphere into the South Indian Ocean in the lower troposphere during the winter has been investigated using grid point wind data at 850 hPa and the data geopotential height field at 500 hPa during 1980—1987. It points out that there are four channels of cross-equatorial flow coming from the Northern Hemisphere near the equatorial area from 35°E to 135°E and they are characterized by considerable annual and interannual variations. The four channels of cross-equatorial from mainly come from the northeast monsoon of continental of continental cold highs ranging from Arabian peninsula through East Asia, the intensity of flow depends on the northeast monsoon activities