Abstract: Using the mangrove plants and sediment of the typical mangrove areas in Guangdong province as research object, the density, storage and spatial distribution of carbon were studied by the combination of wild field analysis and laboratory testing methods. The results showed that the carbon density of the sediment gradually reduced with the increase of depth, and was not affected by the difference of area and tree species. The average carbon density of 50 cm sediment was 0.007 g/g. The carbon density was obviously different in different components of different mangrove species in different regions. The total carbon storage in different regions was the order as Zhuhai 跃Gaoqiao 跃Shenzhen 跃Shuidongwan 跃 Guanghaiwan跃Raoping跃Dayawan跃Chenghai. The carbon density and carbon storage were obviously higher in mangrove covered area than those in blank areas, indicating that mangroves had very strong carbon sink function.