Abstract: The aboveground biomass of Aegiceras corniculatum (L.) Blanco natural forest in Longmen islets of Guangxi was determined in the paper. The aboveground biomass of three natural stands at different ages were investigated with the average standard tree method. According to the data from 18 standard trees of different basal diameter classes, the following regression equations to estimate the biomass of each aboveground organs of A. corniculatum were described from single plant:With significant correlation coefficients, the equations had practical values. The results obtained showed that: (1) The above-ground biomass in 5, 17 and 20-year-old A. corniculatum stands were 743.5g/m2, 7279.0g/m2 and 8817.1 g/m2 respestively. (2) The average productivity were 748.Tg/m2·a,428.2g/m2·a and 440.9g/m2·a respectively.