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The CCS Hydropower Station in Ecuador is characterized by the axis of the diversion to power generation system up to 2 800 m long, the internal and external heads more than 600m, the large groundwater recharge, the developed steeply dipping broken zone and the densely caves criss-crossly arranged, all of these result in gushing water problems during construction and many key and difficult points in waterproof-drainage design. According to the sensitivity analysis of internal water leakage based on seepage field's analysis over various conditions by FLAC 3D, multi-factor instability analysis for wedges considering joints' and fractures' water pressure coupling of in-situ stress by 3DEC, combining with the high-pressure permeability characteristics analysis based on high water pressure tests results, features analysis of the safety monitoring data at the characteristic times after the water-filling test until recently, the research on key technologies for waterproof-drainage and also certification for control measures were finally put forward. Using water-permeable lining, combining with geomembrane, consolidation grouting, curtain grouting for the upstream high-head water diversion system, drainage hole curtain based on drainage gallery and system drainage holes for the downstream power generation system and so on, after all these permanent and temporary combination measures, the power station currently is running well, the safety monitoring data are not anomaly and have been converged for a long time, which certifies the rationality of the waterproof-drainage design for diversion to power generation system under the high internal and external water condition. [ABSTRACT FROM AUTHOR]