A water power generator is provided to enhance the efficiency of converting waterpower into electric energy by changing the side wall of a water striking plate along the stream direction of water to strike water. A water power plant includes an endless trolley(1) and a water receiving plate(3). The water receiving plate is installed on a truck(2) of the endless trolley. The water striking plate includes side plates(4,5). Each of the side plates includes an opening adjusting device. The opening adjusting device opens the side plates in the direction of water stream. The opening adjusting device includes locking units(52), a locking release unit(61), and a side plate rotating unit(62). The locking units are installed at the side plates. The locking release unit releases the locking units. The side plate rotating unit rotates the side plates to be opened in the direction of water stream.
