Abstract: From the compositive analysis for 10 cases of the meridional type persitent and exceptionaliy severe rainstorms,it is found that these rainstorms occurred ahead of the energy front within a stable synoptic situation with a high pressure in north and another high pressure to the east.The upper Ievel subtropical jet stream and the lower level jet stream are the dynamic systems supplying the rainstorm with energy,providing the trigger condition for releasing the latent instability energy.and confining the rainstorm to meso-scale.