Abstract: In a thermal power plant of Qinghai Province, red worm pollution frequently occurs in the pretreatment system of raw water. This paper analyzed the causes of red worm pollution, selects chlorine dioxide as an inactivating agent through experiments, and determines the best dosage and the best contact time. It puts forward the transformation idea of filtering and enriching the red worm in the regeneration water firstly, then batch inactivating it, and provides a specific transformation scheme.