The yearly and seasonal flood and drought status in Rizhao were analyzed based on p recip itation anomalous percentage and Z- index. The results show that p recip itation anomalous percentage reflect the flood or drought degree more lighter, and Z - index canbe more accurate. In this paper the Z - index was used to analyze the flood and drought status from 1955 to 2005 and found that in the 1960 s and 1970 s itwas a flood period and in the 1980 s and 1990 s itwas a drought period in Rizhao, and generally the drought events occuerred more frequently than the flood.．