Sargassum fusiforme is a kind of Sargassum plant of Sargassaceae of Phaeophyta,which grows in the warm temperate zone to the subtropical zone.Dongtou is called “China’s Hometown of Sargassum fusiforme”.In order to clarify the characteristics of dissolved organic carbon (DOC) secretion of S.fusiforme in the process of aquaculture,different gradient treatments such as salinity,light intensity,pH,total inorganic nitrogen concentration in water and total phosphate concentration in water were set up,while simulated aquaculture experiments were carried out.The content of DOC and dissolved inorganic carbon (DIC) in the aquaculture water were measured,and their change rates were analyzed.The results showed that the DOC secretion rate of S.fusiforme medium seedlings was the highest.Under the light intensity of 2 800 lx,the DOC secretion rate and the DIC fixation rate of S.fusiforme small seedlings were the highest.Under the conditions of original seawater salinity of 30,pH of 8,total inorganic nitrogen concentration of 1 mg/L,and total phosphate concentration of 0.02 mg/L,S.fusiforme had the highest DOC secretion rate.Light intensity,salinity,pH,total inorganic nitrogen concentration,total phosphate concentration and other environmental factors all affected the DOC secretion of S.fusiforme,and the effects of different factors were certain difference.