The invention discloses a power generating system used for circulating water recycling. The power generating system comprises a main water pump, water return manifolds, upper tower water valves and upper tower water pipes. The main water pump is used for pumping water in a water collection pond into the water return manifolds, a part of water pumped into the water return manifolds flows into the upper tower water pipes through the corresponding upper tower water valves and flows into a spraying mechanism in a cooling tower along the upper tower water pipes. The power generating system further comprises a water turbine water pipe, a water turbine and a distribution device. The water turbine water pipe is connected with the water return manifolds and is used for conveying partial water in the water return manifolds to a generator set of the water turbine to carry out acting and power generating, the generator set is connected with the distribution device, and the electric energy is distributed to motors of cooling tower draught fans through the distribution device. According to the power generating system, the surplus pressure energy in circulating water can be converted into electric energy, the electric energy is supplied to the motors of the circulating water cooling tower draught fans, and the purpose of saving energy is achieved.