Summer floods and droughts from 1951 to 2006 in Chongqing and East Sich uan are analyzed here by using Z index. It shows that droughts are popular from the end of 1950s to early 1970s, 2 of the 3 most heavy years occur during this peri od. There are both droughts and floods from the end of 1970s to 2003 ，but flood s are more common. 2006 is the most serious drought year in these 56 years from 1951 to 2006. Relation analyses between SST and Z index shows that there exists good relativity between Z index and SST during January and March. Z index has ob viously positive relativity with SST in eastern and medial equatorial pacific oc ean. In heavy floods year SST anomalies are prominently positive. On contrast i n droughts years, SST anomalies are obviously negative. Negative anomalies from January and March are contributable for the serious droughts in 2006.