The utility model discloses a flat water flow hydraulic generator, which utilizes the kinetic energy of flat water flow to anchor the hollow double-layer semi-submerged seat with a turbine and a generator in water. On the bottom plate below the water surface line of the seat, a plurality of cylindrical turbine impellers are arranged perpendicularly in a transverse line crossed with the water flow, fittingly equipped with a diversion base with a concave half circular diameter of the impeller and a diversion cut. The water flow between two diversion bases is used to impact the half circular diameter of the impeller to rotate around the axis. And superposed torque is transmitted among wheel axle heads in a belt drive mode to drive the generator for electricity generation. The generator can be used in places with flat water flow and has flexible layout and common use.