Mangroves have an important role and great function in environmental protection and coastal ecosystem. Mangrove forest also has a role of climate regulation, reducing greenhouse gases and contributing to climate change mitigation. Therefore, forest biomass estimation is nescessary for suitable forest management. This study apply three types of low and medium resolution imagery (including MODIS, SPOT and LANDSAT) with the application of NDVI index (Normalized Difference Vegetation Index) to determine mangrove forest species distribution in the Dat Mui Commune, Ngoc Hien district, Ca Mau province. The study area are dominated by jour main species of mangrove forest, including: Rhizophora apiculata blume, Avicenna alba, mixed forest and combination system of shirmp and mangrove forest. The result shows that two of three images used to determine mangrove forest are of high reliability (i.e. 94.72 percent and 96.14 percent of SPOT and LANDSAT images, respectively) and of low reliability (i.e. 34.3 percent of the MODIS image). Total mangrove area is 9.555,21 ha in which the shrimp and mangrove forest combination is of the greatest (approximately, 48,48 percent)
next to that, rhizophora species (27,2 percent) and avicenna species (20,6 percent) are of the sequences while the lowest area is of the mixed forest (4,25 percent). Moreover, fresh biomass of each forest species is identified based on ages and trunk diameters with the greatest distribution on avicenna species (214,92 kg/ha/year), rhizophora species (188,42 kg/ha/year) and the combination system of shrimp and mangrove forest (113,05 kg/ha/year) with ratio between mangrove forest and shrimp at 6:4.