Abstract:The flora and distribution of macroalgae as well as the biomass of its two dominant species were studied in mangrove forests in Fujian Province, China. There were totally 42 species belonging to 24 genera of macroalgae, in which 15 species/8 genera belonged to Cyanophyta, 7/3 to Rhodophyta, and 20/13 to Chlorophyta. The biomass of the dominant species Caloglossa leprieurii and Catenella impudica were 2.22 to 8.44 g/m2 DW and 2.69 g/m2 DW in June,and 0.15 to 0.20 g/m2 DW and 2.12 g/m2 DW in December, respectively. On the tnmk surface of the mangrove plants,macroalgae appeared vertically to be distributed from lower upwards into six belts, namely Vaucheria sp. belt, Catenella impudica belt, Caloglossa ogasawaraensis-Bostrychia mixta belt, Calogiossa leprieurii belt, Chaetomorpha macrotona-Rhizoclonium riparium belt, and Chlorococcum sp. belt.