Based on floods records at Ankang reservoir and Lintong observation station from 1960to 2000,the occurrence characteristics of floods were comparatively analyzed between the upper reaches of HanjiangRiver and Weihe River.The results showed that there were common feature between those two basins interms of flood.The years recorded as extremely large floods in two basins were closely related to the yearsthat had heavy autumn rainfalls in Southwest China.The extreme floods did not always occur in the veryyears that had extreme rainfalls in Southwest China,but right prior to or after those years.As affected byAsian monsoon and regional climate environment,the extreme floods mainly occur in early summer andwhole autumn in upper reaches of Hanjiang River,while in mid-summer and whole autumn in reaches ofWeihe River.Flood occurred generally earlier in upper reaches of Hanjiang River than in Weihe River basinduring ayear,while in autumn flood come earlier in Weihe River basin than in the upper reaches of HanjiangRiver.These findings could provide basic information for weather forecasting and flood controlling in thesetwo basins.