The multipurpose optimization model for operating rulecurves was established and used to simulate the operation of reservoir. The Danjiangkou Reservoir was selected as the case study, and 10 day runoff series from 1961 to 2010 was used as the reservoir inflow. It is shown that the multipurpose optimization operation can generate extra 0.414 billion m~3 ecological water supply (or increase 3.21%) and 0.081 billion kW·h power (or increase 2.13%) than those of the design operating rule curves, respectively. The assurance probability of ecological water supply, annual average ecological water supply and power generation were improved in the multipurpose optimization operation without increasing flood control risk and no significant impact on water supply of downstream and south-to-north water diversion. The impact analysis of runoff made with the outputs from GCM (global climate model) as input of the VIC (variable infiltration capacity) distributed model, predicted the runoff change for future 90 a in the Hanjiang basin. Multipurpose reservoir operating rule curves can effectively adapt to the climate change.