The Caiziba Pumped-Storage Power Station, China’s pioneering large-scale project in a complex karst region, faced daunting geological challenges. Led by the Shanghai Investigation, Design & Research Institute (SIDRI), the team needed to navigate extensive cave systems, severe seepage, and inherent collapse risks. To master this complexity, SIDRI embraced a cutting-edge, fully parametric, multi-disciplinary digital twin system, leveraging the Bentley ecosystem, including MicroStation, OpenBuildings Designer, PLAXIS, ProjectWise, and iTwin. This digital approach delivered powerful breakthroughs, dramatically improving efficiency: core hydromechanical equipment modeling was completed 75% faster, while the 3D review system identified and eliminated 1,850 design conflicts, successfully avoiding RMB 4.5 million in potential rework costs. Furthermore, the use of ProjectWise boosted cross-disciplinary collaboration by an impressive 80%, accelerating the critical design path by 42 days. These precise digital methods also yielded significant Green Outcomes through material optimization, reducing concrete usage in a single water conveyance system by 3,200 m3 and cutting steel usage by 860 tons, a saving equivalent to 2,150 tons of CO2 emissions. Ultimately, the station’s frequency regulation capacity was enhanced by 30%, enabling the grid to reliably absorb 210 million kWh of wind power annually, thereby providing crucial support for the nation’s Energy Transition.