Abstract: A wide-range continuous rainstorm process occurred in southern China in June,2005,and led to severe flood,landslide and caused great damages in the region.This paper makes the diagnostic analysis of the rainstorm process by using conventional meteorological date,satellite cloud images,TBB and data of T213 analysis field,and finds: The sufficient and stable vapor of the rainstorm process mainly originates from the Indian Ocean,which is different from the previous ones coming from the South China Sea such as the June 1994 rainstorm.The high and low level jet streams and shear line are the triggering system.The low-level jet stream maintains convectively unstable situation on low levels.The upper one supports symmetric unsteady condition on upper levels.The cold and warm currents meet at the southern side of the shear line and the left side of the low-level jet stream to produce an upward movement of intensive convergence and trigger the rainstorm.The direct reason of the sustained rainstorm is that MCS kept growing and decaying in the convective clouds.There was a change of high-level jet stream in which the direction of high altitude jet stream turned to southwest from northwest,and the change tendency of the shear line was corresponding with it.This characteristic is also an important reason that the rainstorm process could maintain.