Abstract: The social-economic dynamic model(SEDM)reflecting land use and land cover(LULC)variation is coupled with the regional climate model(RegCM3)and used to simulate the regional climate change in north China as if a large scale of agriculture and pastureland is irrigated after the completion of the South-to-North Water Transfer Project(SNWTP).The preliminary simulation results show that the large-scale agriculture irrigation might cause significant regional climate change in China1 During the most possible irrigation time of summer months from June to August,the ground temperature,sensible heat flux as well as the potential height at 500 hPa are all decreased within the irrigated region and the adjacent areas,while the low-level air humidity,cloud cover,latent heat flux and precipitation are all increased.The large-scale agricultural irrigation not only changes the water vapor factors of soil moisture and air humidity,but also the thermal factors,such as temperature,the sensible heat flux,the dynamic factors of potential height and wind field in the atmosphere,which cause the regional climate change in the whole numerical domain.