Abstract: It is revealed that the mean meridional circulation in the tropical Pacific ocean has two different basic patterns:Hadley cell and Anti-Hadley cell. The transformation of one type of the mean meridional circulation to the other not only has the seasonal variation but also the non-seasonal long-term variation. The intensity of meridional circulation has a long-term fluctuation with the period of 32-48 monthes. It is also found that the transformation of mean meridional circulation patterns is closely connected with the variation of the vertical circulation on the vertical plane along the equator. There exists a low-frequency coupling oscillation between them. The transformation of atmospheric vertical circulations would have some importent influences on the long-range weather variation in this region.