Abstract: The concentrations of dimethyl sulfide in the seawater of coastal area in Xiamen were determined in April and November of 1993 and the fluxes of DMS from the ocean to the atmosphere were estimated.The monitoring results show that the concentration range of DMS in seawater was 191~365ng/L with a mean value of 288ng/L in spring and 119~351ng/L with a mean value of 215ng/L in autumn;there was a obvious diurnal variation for the DMS concentration in the seawater,and the maximum of DMS concentration was at midday and minimum at midnight.The estimation results of DMS flux show that the DMS flux was 16.12μmol/(m²·d) in spring and 29 84μmol/(m²·d) in autunm;DMS flux in autumn was ovbiously more than that in spring,and this was because of the difference of DMS exchange constant caused by different wind speed on sea surface in spring and autumn.