Abstract: With the advantages of wide spectrum, high efficiency, environmental protection and low toxicity of 4, 5-dichloro-2-n-octy-4-isothiazolin-3-one (DCOIT) , DCOIT has gradually become a new antifouling agent to replace organic tin (TBT) . Here are summarized the environmental destination of DCOIT and its ecological toxicity judgment basis and introduced the applications of DCOIT in antifouling material and its antifouling effect, and is reviewed the controlled release technology of DCOIT antifouling agent in recent years. Finally, the future application and development of the antifouling agent are prospected.