With the hydrological model SWAT, the runoff variation of three representative watersheds in Dongjiang River Basin was simulated.With discharge data from Shengqian, Shuntian and Jiuzhou hydrological stations in 1977-1981 and 1996-2000, more sensitive hydrology factors were calibrated and satisfactory simulation results were obtained (R²>0.85, 0.68 <E_NS <0.75).The study investigated the influences of LUCC on the hydrological process of the three watersheds.The result shows that:(1) the in-crease of forest area was the cause of annual runoff decrease;(2) in terms of annual variability, runoff decrease in the wet season while increase in the dry season;(3) the decrease of runoff becomes more notable when the forest area increases with slope <15°.