The technical documents， the experts' knowledge and experience， and the operating states of hydro-turbine generator sets are digitized with modern modeling and simulation as well as computer and network techniques. The digital information can be understood not only by human experts but also by intelligent equipment. They are extensively employed in the condition analysis and diagnosis of hydraulic generating facilities. A digitized condition analysis and diagnosis system of hydro-turbine generator sets has successfully been developed and applied in 6 sets at Gezhouba Hydropower Plant. A wide area network for condition monitoring and diagnosis of hydro power stations and substations at Gezhouba has been established. The condition monitoring and diagnosis can be carried out remotely. This system has made significant contributions to prevention of unexpected facility outage and performing condition based maintenance.