Abstract: The drought-flood abrupt alternation events, caused by the subtropical monsoon climate, occur frequently in the Hanjiang River Basin, which have negative impacts on the economic and social development. Therefore, we adopted the SWAP and SRI to analyze the characteristics of the drought-flood abrupt alternation events in the Hanjiang River Basin. The results show that: (1) The SWAP and SRI have good applicability to identify the drought-flood abrupt alternation events. (2) From the northwest part of upstream to the southeast part of downstream in the Basin, both the frequencies of the droughts and the drought-flood abrupt alternation events decreased first then increased. The average intensity of the drought-flood abrupt alternation events presents an increasing trend. From north to south of the Basin, the frequencies of floods show an increasing trend. (3)The droughts can occur at any time, while most floods and the drought-flood abrupt alternation events occur in the summer. Moreover, the drought-flood abrupt alternation events are usually serious and risky.