Abstract: Addressing the issue of zero discharge of circulating water is one of the most crucial fundamental tasks for achieving zero wastewater discharge in wet cooling thermal power plants. In 2022, the production water source of Shanxi Electric Power Co., Ltd. Hejin Power Generation Branch (hereinafter referred to as Hejin Power Plant) was switched to urban reclaimed water. After pretreatment, the water quality was used as makeup water for circulating water, resulting in high salt content and hardness in the circulating water. Based on the quality of the circulating water, Hejin Power Plant adopted the "double alkali method" pretreatment process to remove the hardness from the circulating water blowdown. After meeting the conditions, it entered the "ultrafiltration + reverse osmosis" treatment system for pre-desalination. The reverse osmosis permeate was used as raw water for the demineralized water station, while the remaining part was used as makeup water for circulating water. The concentrated water produced by reverse osmosis was replenished to the desulfurization process water system, thus achieving zero discharge of circulating water. This exploration and practice have been carried out for subcritical wet cooling power generating units using reclaimed water as the source to achieve zero discharge of circulating water.