The invention relates to a sterilization and electrolytic descaling method for circulating water. The method is characterized by comprising the following steps: firstly, pretreatment: the to-be-treated water is fed into a pretreatment tank for treatment to remove particles and organic matter in the water and reduce turbidity; secondly, electrolytic reaction sterilization: the pretreated water enters a total water inlet pipe of an electrolysis reactor, then enters a micro-electrolysis barrel through branch pipes connected onto the total pipe, scale caused by microorganisms is blocked, and thenthe water converges to a total water outlet pipe; thirdly, descaling by a descaler; fourthly, descaling by a scale collector. The sterilization and electrolytic descaling method for the circulating water has the advantages of being good in descaling effect, preventing secondary water pollution, and being environmentally friendly and energy-saving.