Abstract. The potential impacts of climate change on individual hydropower system have been addressed in many studies, but the generation influence of a cascaded hydropower system is seldom to be noted. In this paper, a maximum firm capacity optimal model was simulated for the 5-cascaded hydropower system under the 3 climate change scenarios, RCP4.5-GFDL, RCP4.5-GISS, and RCP4.5-IPSL in Lower Lancang River. The calculation results show the RCP4.5-GISS scenario would heavily decrease the generation energy, and the huge reservoir can make a good adaptive capacity to the climate change for a cascade HPPs system.