The invention relates to a circulating water hydroelectric power station constructed through interaction of self weight of water bodies and buoyance. The circulating water hydroelectric power station comprises a partitioning reservoir, a water injection pump, a water injection pipe, a water supply pipeline, a water tank, a water delivering pipe, a water turbine, a water pumping cylinder body, a water replacing box body, a gravity cylinder body, a buoyance box body, a water pumping cylinder body piston disk, a gravity cylinder body piston disk, piston disk connecting rods and a water replacing box body drain pipe. Through the adoption of the technical scheme adopted by the circulating water hydroelectric power station disclosed by the invention, under the premise of without dependence on or drawing support from other outside force, and without consumption of energy sources such as fossil, only the original self weight of the water bodies and the characteristics of the buoyance are utilized, the self weight of the water bodies and the buoyance mutually utilize the force of the other part in a device system which is artificially mounted, so that after the water bodies and required water quantity continuously and automatically operate to any required height which is artificially set to form a required drop height, and then through a water guiding device system and a water delivering pipeline, the water bodies and the water quantity flow past the water turbine, so that the water turbine acts to produce electric energy.