Replacing the RegCM2 runoff scheme with the heterogeneous surface runoff algorithm which is suitable to the loosen and compact soils,this paper designs a hydrological model being coupled with RegCM2,and simulates the discharges of the two important hydrological stations in the Yangtze basin,which are verified by the observation value.The monthly precipitation of June,July and August 1998 during the rain storms is simulated by the coupling model,and the impact of the runoff scheme on simulated precipitation,surface heat fluxes,runoff and soil moisture is analyzed.The results show that(1) the runoff scheme is reasonable for simulating the precipitation distribution during the rain storms in 1998,and improves to some extent precipitation simulation,about 10% of total precipitation;(2)the runoff scheme changes timely the heat fluxes from the surface to the atmosphere which are connected with the reassignment of the surface water;(3)this scheme enhances the soil infiltration,resulting in less runoff during the early period of rainstorm,and more runoff during the last period;(4)the consistency of simulated and observed discharges shows that the coupling model has capacity to represent the hydrological process in the Yangtze basin during the heavy rainstorms in 1998.