Abstract: The hydro-wind-photovoltaic hybrid energy system is an important way to build China’s new power system and to peak carbon dioxide emissions by 2030 and achieve carbon neutrality by 2060. The advantages include orderly developing renewable energy combined with natural resources condition at power sending terminal, effectively improving the consumptive ability of power grid for wind and photovoltaic energies, and significantly increasing the utilization rate of power transmission channel and the competitiveness of electricity price. The hydro-wind-photovoltaic hybrid energy system, with a total installed capacity of more than 10 million kW, is mainly driven by cascade reservoirs. However, due to the combination of wind and photovoltaic energies with hydropower, cascade reservoirs are faced with more difficult challenges, including larger input uncertainty, new operation constraints, and more complex coordination. Moreover, existing studies vacillating in a wide range of research spectrum are applied to the limited real-world projects with small installed capacities, and are not summarized systematically yet. Therefore, based on plenty of investigations in excellent work by international experts and scholars, this paper intends to provide the state-of-the-art review of hydro-wind-photovoltaic hybrid energy system, involving its development and utilization, its planning and designing, and its regulation and operation. The main research problems are also summarized, and then future potential suggestions are discussed. Accordingly, this paper will provide helpful technical suggestions and ideas for the development and management of the hydro-wind-photovoltaic integrated renewable energy bases listed in China’s 14th five-year plan.