A heavy rainfall during 5—7th June 2006 in Fujian province was simulated by the WRF mesoscale numerical model.Diagnoses were made based on the output data,to get the structure of the rainstorm and the influence of complex topography.Results show that,the WRF model successfully revealed the circulation’s evolution and the distribution of rainfall belt.It was a typical South China quasi-stationary precipitation which was associated with the stationary front,low-level wind shear and low-level jet.The convergence of the low-level flows intensified the ascending motion which triggered the release of potential instable energy,resulting in the genesis and maintenance of the rainstorm.The vertical configuration of potential temperature was found favorable to the development of vorticity at low level.With the help of Bell-mouthed terrain and the windward slope of the Wuyi mountains,southwest airflow veered and converged at low level,resulting in the form of mesoscale shear and vortex.Warm and wet air was raised by the mountain,thus enhancing severe convection at the middle-level.All of the above factors reinforced the rainfall at Jianou,Shaowu and Pucheng on the windward slope.