The invention provides an ultra-large hydropower station. Flowing seawater and river water can be used for generating kinetic energy which is converted into mechanical energy, and the mechanical energy is converted into electric energy, so that clean and low-cost electric energy can be used by human beings. The ultra-large hydropower station is characterized in that an axle core of a water turbine is movably fixed, and the water turbine position is unchanged; the water turbine is arranged horizontally on flowing water in the water flow direction, with one half in the water and the other half in the air; the water turbine is driven to rotate by blades under hydraulic push, and the water turbine is rotated to drive a generator for power generation, so that the electric energy is generated day and night. The hydropower stations are arranged longitudinally and horizontally on the sea and river, covering an area of tens of thousands of square kilometers, so that tremendous amounts of electric energy are generated and supplied all over the country. The ultra-large hydropower station belongs to the field of clean energy and renewable energy, and the generating cost is minimum; even if the population of China reaches 5 billion after 1000 years, the power supply requirements can also be met; the problems of energy sources, haze and climate change in China will be solved thoroughly, and the hydropower is a unique correct method for development of electric energy and energy sources in China at present.