The surface energy flux balance and total evapotranspiration were estimated using the eddy correlation, and bandpass covariance technique over a tropical monsoon environment within the framework of GAME. One of the aims of this present study is to obtain information on the seasonal variation of heat and water vapor exchanges between the atmosphere and terrestrial land cover (complex area) in tropical monsoon environment. The result indicated the daily integrated values of net radiation, sensible heat, latent heat and ground heat flux during the observation period from July 1998 to February 1999 were 10.76 MJ m-2, 2.32 MJ m-2, 5.18 MJ m-2 and 0.03 MJ m-2, respectively. Sensible and latent heat fluxes were the dominant energy partitioning components throughout the year. The seasonal difference in surface fluxes between wet and dry seasons was seen, and the latent heat flux was dominant in the monsoon season, corresponding with the increase of specific humidity after frequent precipitation. Whereas the sensible heat flux increased as the surface temperature increased in the absence of rainfall during the dry season. However, the closure of energy balance remained unresolved as with the foregoing experimental studies. The estimated amount to evapotranspiration was 526 mm versus 641 mm of actual precipitation, and accounted for about 80% of the precipitation during this period. Over typical land uses in monsoon region the short-term observation was conducted to measure the CO2 flux. The results suggested that both of land uses might work as the carbon sink throughout a year even in the crucial dry condition. The comparison of model parameters, which indicate the intensity for evaporation and the net assimilation rate, indicated that the activities of the paddy field was more vigorous rather than that of the terrestrial terrain.