The microplankton phytoplankton community in the coastal community of Trang found in the Tropical Oyster culture area consists of 38 phytoplankton that can be classified to the genus level, with Class Bacillariophyceae being the group that has highest element It has a higher density than other groups, more than 99% of the density of 30 genus of phytoplankton, followed by Class Dinophyceae. In June, it was found to have a higher density than other groups. Accounting for more than 70% of the total phytoplankton density, 5 genus Class Cynaophyceae 2 genus and Class Dictyochophyceae 1 genus.