The Kur-Qian p-σ incorprated coordinate five layer primitive equation spherical band(70°N+30°S)model is adopted in this study with effects of Ural blocking high introduced thereinas initial and boundary conditions to investigate the high’s influence upon East Asian summermonsoon circ u lation and dryness/wetness over eastern China with the aid of case contrast andcontrol experiments. Results show that the blocking high as an excitation source is responsible fora SE-NW stationary wavetrain with its upper level anticyclonic divergent circulation(a troughbeneath)lying just over the mid to lower reaches of the Changjiang,which reinforces East Asianwesterly jetstream,beneficiaI to disturbance development and produces an additional secondarycirculation meridionally at the jet’s entrance as well, thus strengthening updraft over the EastAsian monscon region.As such, the Ural high and the related wavetrain represent the large-scale key factor and controlling mechanism for excessive rainfall in the Changjiang-Huaihe valley.