The aim of this study is to assess the potential of carbon sequestration in aboveground biomass and net primary productivity (NPP) of Thong Pha Phum forest. Following two procedures are applied data estimation: 1) aboveground biomass estimation 2) NPP estimation. The method of the first one was based on inventory for DBH stem at is more than or equal to 4.5 cm by allometric equation an aboveground carbon stock was calculated by multiplying conversion factor as 0.5 of biomass. As the results, carbon sequestration had varied in different types of forests that tropical rain forest (Ton Mai Yak and Ban Passadu Khlang station) is higher than dry evergreen forest (KP 27 station) and mixed deciduous forest (Pong Phu Ron station) as 137.73+-48.07, 70.81, 70.29+-7.38 and 48.14+-16.72 tonne C/ha, respectively. Because the variables of habitats have caused differences in biomass accumulation, species composition and the allometric relationships of forests. In the study area, all forest have a similar pattern of tree size class, with a dominant size class at is more than or requal to 4.5-20 cm, these smaller trees have the lowest carbon sequestration potential but they are relevant mainly in terms of their future potential to go to the further size classes and they will be able to increase biomass and store more carbon. The other one, NPP estimation is based on the Miami model extended by functions considering annual mean temperature and precipitation. The aboveground NPP is 10.34 tonne C/ha/year and the result indicates that the best estimate of NPP in this study is from the annual mean precipitation rather than annual mean temperature cause of the study area is located in the tropical zone where the light intensity and temperature are unlikely to be the limiting factors for the NPP.