Abstract: In this study, the total phenolic and flavonoid contents, antioxidant activity and volatile components of brown seaweed Sargassum muticum were investigated after treated with charcoal suspensions at concentrations of 5%, 10%, and 15% (w/v) for 6, 12, 18 and 24 h, respectively. Results revealed that the total phenolic content was reduced by 71.90%, 74.1% and 76.5% respectively compared to the non-charcoal treated control after 6 h of 5%~15% charcoal treatment, while extending treatment time had little impact on it. The total flavonoid content did not differ significantly from the control at 6 h with 5% charcoal treatment (P>0.05) and decreased slightly with longer treatment time, whereas it decreased significantly with both 10% and 15% charcoal treatment to 68.2% and 60.0% of the control after 24 h, respectively (P<0.05). For antioxidant capacity, the scavenging activities of ABTS⁺· and DPPH· were both reduced after charcoal treatment, moreover the differences between different charcoal concentrations were not significant at first 6 h (P>0.05), whereas decreased gradually with charcoal concentration elevated after 12 h. A total of 25 volatile components were identified from S. muticum, of which the content and types of hydrocarbons dominated. The relative content of volatile components decreased significantly after charcoal treatment (P<0.05), especially the key odor compounds (aldehydes) decreased by 58.8% of 15% charcoal treatment for 24 h, indicating that deodorization using charcoal could effectively reduce the fishy flavor of S. muticum samples. These results provide reference and basis on development of S. muticum for functional food products.