Based on the low frequency windfields, study is made of the difference in low-frequency oscillation (LFO) between flood-and drought-hit years and the relation to rainfall. Results suggest that in such years the low-frequency component makes up greatly varying portion for the circulation systems in east China and the MLCB (mid-lower Changjiang basins) rainfall-related wind features and variation are quite distinct; in 1980 as the flood year over the MLCB the change in precipitation is closely associated with the LFO in the East Asian monsoon region, especially in subtropical monsoon, with its northward propagation in a phatic manner, marked by a quasi-8 pentad period, thus responsible for the periodic variation in rainfall whilst in 1988 as the year of drought the rainfall change bears no relation to East-Asian monsoon′s LFO but to a vigorous low frequency vortex dominating the northern portion of East Asia, which originates from the one over the waters east of Japan moving north and then turning west, and the movement and development are at a quasi-8 pentad period, too, leading to change in rainfall over the MLCB.