Based on a high-resolution underlying surface GIS dataset that extracted from the Landsat TM, a high-resolution simulation experiment by using the Weather Research Forecasting (WRF/NCAR) numerical model coupled with Urban Canopy Model was conducted to analyze summer climate effects and its differences of Beijing-Tianjin-Hebei megapolis area under different development prospects. The results showed that, 1) City layout impacted regional climate obviously, and small differences of city layout would reduced on climate differences of larger area; 2) Different development prospects of megapolis area had different effects on regional climate, in addition, the strongest climate effects would caused by centralized development model, then balanced development and bead type development model would resulted in stronger climate effects, and grade development model would produce a relatively weak climate effect; 3) That urban development influencing on air temperature was more obviously in the night than daytime; Urban heat island was strongest in the night which influenced on larger area but lower height; however, it is on the contrary during the daytime that made the intensity of inversion layer weaken; moreover, that phenomenon of wind and relative humidity impacted by urban development was more clearly in the daytime than night. 4) Urbanization was mainly influence on precipitation distribution; moreover, Rain Island was multicenter structure and principal part mainly located on the fringe of city downwind. Urbanization may cause frequency decrease of weak precipitation, but the average rainfall intensity would increase, on the contrary, frequency of strong precipitation may increase but rainfall intensity weakened.