Existing study show that 80% exploitation of water resource in Laos would induce power trade between the countries and would become the net energy exporter, earn significant export revenue, and improve the increase in revenue of energy export per increase in total energy system cost from the maximum exploitation of hydropower resource, the integrated energy system cost is found to decrease marginally. The finding indicates that cross-border power trade between the two countries could contribute positive effects in terms of CO2 and local pollutant emissions to Thailand, whereas Laos would not have the significant impacts. Thailand is expected to gain benefit from the increased level of power imported from Laos in terms of the lower energy system cost, better environmental quality and, greater diversification of energy sources.