Abstract: In this paper, a concret analysis was made on the characters of the low frequency wind and velocity potential fields around the time of Meiyu. It is found that remarkable distinct circulation patterns in the low frequency wind fields around the globe not only exist in the drought (1981,1985,1988) and flood (1980,1983) years,but also exist in the stages of the drought (or flood) years when precipitation is increasing or decreasing. Concentrating on the years of 1980 and 1988,we find that it is caused by the wave in the low frequency velocity potential fields which connect the precipitation in the Changjiang River valley with the low frequency wind fields around the globe.In the year of 1980,precipitation responds quite well to the northward propagation of LFO in the East Asia monsoon region and the vortex train propagating eastward in the high latitudes of Southern Hemisphere. In the year of 1988,variation of precipitation was closely rela ted with the movement of the low frequency vortex which originates from the small low frequency vortex in the east of the tropical Pacific. It is thought that heat/cold source pattern and Wal ker circulation can be the mechanism which affects the precipitation, while the mechanism in 1988 remains to be discussed.