A faster rate of needle litter decomposition of Pinus kesiya occurred in forest site I (undisturbed) with losing 98% of the initial mass in comparison with 96% of mass loss for forest site II (disturbed) over 24 months. Decomposition rate shows seasonal changes with the maximum rate in rainy season and minimum in dry winter season. Needle litter of forest site I exhibited higher initial concentration of nitrogen, cellulose and lower lignin and lignin to nitrogen ratio than forest site II. The rate of decomposition was correlated with soil moisture (r = 0.51**, 0.51**); soil temperature (r = 0.55**, 0.52**) than rainfall and mean air temperature in both forest sites. Chemical composition like initial nitrogen, lignin, lignin to nitrogen ratio and cellulose were significantly correlated with remaining biomass. (r = 0.78, 0.95, 0.95 and 0.81) in forest site I and (r = 0.62, 0.90, 0.91 and 0.75) in forest site II at the level of P < 0.01 in both forest sites. The decay constant were 0.594 and 0.582 in forest site I and site II respectively. During decomposition, concentrations of nitrogen and phosphorous were found to increase whereas potassium and sodium exhibited decreasing pattern from the original concentration in both the forest sites. The average concentration of nutrients in both forest sites was in the order N > K > P > Na. The release of nutrients (N P K and Na) based on the amount of element remaining over two years in forest site I and forest site II was in the order K>Na > P > N.