This paper simulates the effect of urban hydrological processes such as green irrigation, oasis effect and artificial latent heat in Beijing on the urban meteorological environment, using the WRF/SLUCM scheme during a lasting heat wave on July 4-6, 2010. The results are shown as follows. (1) The model can improve the latent heat flux up to 100 W·m^-2 at 13:00, and 15 W·m^-2 at 02:00, and the sensible heat flux decreases up to 80 W·m^-2 at 13:00, and 5 W·m^-2 at 02:00. (2) The model can improve the relative humidity up to 4% at 13:00, and 6% at 02:00, and the surface temperature drops 1.2℃ at most at 13:00, and 0.4℃ at 02:00. (3) The weakening effect of urban hydrological process on the urban heat island in Beijing is significantly weaker during the day than at night, and a cold island effect with an intensity value of 0.8℃ occurred at 10:00-14:00. (4) The urban hydrological processes cause the air temperature decreases by 0.5℃ at most and the relative humidity increases by 3% below 500 m during the day in urban areas. Due to poor thermal convective motion, the boundary layer height decreases at about 200 m; the wind speed increases above 1 km, while the wind speed reduces in the lower layer.