The invention relates to an experimental device for attracting fish and replenishing water at a fishway inlet of a hydropower station, which belongs to the field of water conservancy project facilities. The device comprises a fish attraction retaining wall, a flow control grid formed by two pore plates, an energy dissipation section, two water outlets, two fishway inlets, three fishway retaining walls, an isolation net, two control gates and other components. The control on water flow and flow velocity is realized through adjusting relative positions of the two pore plates of the flow control grid; a fishway inlet is arranged between every two adjacent fishway retaining walls; the control gates are arranged between the water outlets and the fishway inlets. The experimental device can control the water flow and the flow velocity at the fishway inlet, is high efficient and affordable, and integrates attracting fish and replenishing water effects into a whole, is simple in structure, convenient to operate, reliable and stable, and low in cost, and is remarkable in fish attracting effect through adding an attracting fish and replenishing water flow at the fishway inlets to form a fish attracting water flow so as to attract the fish to enter the fishway, and is suitable for being promoted and used in water conservancy projects.