The papers present the results of a survey in the mangrove forests and estuaries of Tra Vinh. There are 415 mub crab larvae collected from 2008 to 2009, in the larval net is 177 individual and 238 in net "xiep", of which there are two species of mud crabs (Scylla paramamosain): 342 individuals (82.4 percent) and (Scylla sp.): 73 individuals (17.6 percent). Morphological characteristics of the variety described for the stage megalop and juvenile. The density of larval in the mangrove forests are 1.13 ind/l0m2, December 2008 has the highest density is 1.90 ind/l0m2, followed in February 2009: 1.43 ind./l0m2, April 2009: 0.68 ind./l0m2 and the lowest was in July: 0.53 ind./l0m2. Megalop density obtained in the estuary with an average 3.27 ind./l00m3. December 2008 has the highest density is 5.98 ind./l00m3, followed in February 2009: 3.65 ind./l00m3. April 2009: 2.44 ind./l00m3 and the lowest was in July: 1.03 ind./l00m3. Crabs collected in the. mangrove forests have a larger width carapace that in the estuary compared with 2.24 mm to 7.64 mm.