This paper assesses the impacts of climate change on runoff and reservoir operation and derives adaptive reservoir operation rule curves for future climate change scenarios. The Xin'an River hydrologic model was applied in a case study of the Xin'an River reservoir to generate its monthly runoff from 2016 to 2045 in the climate condition based on the outputs of the BCC-CSM 1.1 model under the scenario RCP 4.5. Then we were able to use the runoff data to evaluate the impacts of climate change on runoff and reservoir operation and derive adaptive operation rule curves for this reservoir. The results show that relative to the reference period of 1971-2000, annual mean runoff will decrease by 5.0% and inter-annual and intra-annual runoff variations will also decrease. And power generation will be reduced by 3.0% in its annual mean and its intra-annual distribution will be changed. Compared with the past years' operation curves, this new adaptive rule can increase annual mean power generation by 0.5% and save mean reservoir spill by 19.6%. Thus the adaptive operation rule curves can better adapt to future climate change scenarios and fulfill the potential of reservoir operation.