The total Meiyu precipitation in Anhui province in 1996 is nearly identical with that in 1991.But the economic losses caused by flood and waterlogging is only half of 1991′s.The unstable torrential rain with characteristic of variable falling area during 1996 Meiyu season is the principal factor,and the concentrated torrential rain regions towards to the south and the less precipitatin on in earlier stage of Meiyu season are aslo important factors.By the contrast analysis on the circulation characteristics and the impact system between the stable torrential rain and the unstable torrential rain,the preliminary research way that can be used to estimate the damage situation in large Meiyu precipitation year is given.