Using a regional climate model(RegCM3) which is nested in one-way mode within the NASA/NCAR finite volume element CAM30, the effects of stomatal resistance variation on the surface hydrology and heat balance over Poyang Lake Basin is simulated by employing the present-day climate from 1992 to 1997 and doubled atmosphere CO2 concentrations.The result shows that the doubled stomatal resistance in the present climate results in an increase in the annually averaged surface air temperature of 033 ℃（193%）and a reduction in annually averaged precipitation of 023 mm (24%). If both the atmospheric CO2 content and the stomatal resistance are doubled，the regional response of surface air temperature and precipitation are increase in 202 ℃(119%) and 068mm/d(71%) compared with 169 ℃(996%) and 083mm/d(86%) if CO2 is doubled but stomatal resistance remains unchanged as in the usual “greenhouse” experiment.Overall, the impact of doubling stomatal resistance can be as large as the effect of doubling atmospheric CO2