Based on the data of Wuhan,Jingzhou,Yichang,Yunxian,Enshi,a drought/flood grade series of Hubei province in the period of 1470—2000 is established.The variation of drought/flood is analyzed.It demonstrated that,in the last 531 years,there're 8.8% more floods than droughts in Hubei province.The recurring period of serious flood was 48 years and that of serious drought was 59 years,and the lasting period of drought was longer than flood. And the 20th century was a century that there were the most drought and flood disasters within the period of 1470—2000,and the first half of 19th century was the most wet period of 50 years.The transformation periods in different centuries were different,and the major periods were 20-,10-11-and 5-6-year.