Water-in-series water saving method of circulating cooling water system of steel rolling process

The invention relates to a water-in-series water saving method of a circulating cooling water system of a steel rolling process. The water saving method is characterized by using sewage of the indirect cooling open type circulating cooling water system to rinse an ultrasonic probe in a flaw detection process step; taking rinsing water as supplementary water of a direct cooling open type system of a rolling machine after coagulation sedimentation treatment; and taking the sewage of the direct cooling system of the rolling machine as the supplementary water of a direct cooling system of a casting machine and a product direct cooling system. The water-saving method has the advantages that: by using the water saving method disclosed by the invention, the supplementary water of the steel-rolling indirect cooling open type circulating cooling water system adopts industrial fresh water, the supplementary water of the direct cooling system completely adopts water in series, and the water used for the flaw detection p