In view of the specified design conditions of Three Gorges Project (TGP), the main technical problems that should be considered in the design of hydro turbine generating units are analyzed. The key technical researches performed are summarized and the parameters of hydro turbine generating units are optimized through the study on key technical problems. The unit operation results indicate that the performance of the hydro turbine generating units is excellent, and the units can operate in a safe, stable and highly efficient mode for a long term. Therefore, it is verified effectively that the general technical design of giant hydro turbine generating units is scientific and rational.