Abstract: Using the routine observation data and NECP reanalysis data,a case of a regional rainstorm occurred in Eastern Tibetan Plateau from July 7th to 8th,2013 was analyzed.The results show that:the shear line in northern Tibetan Plateau was the major affecting system and the strengthening of outhwesterly airstream was the direct infection.The coordination of convergence at the low levels and divergence at the high levels,which resulted in strong updraft motion,provided favourable ynamicconditions for this rainstorm.At the same time,the high-temperature and high-energy atmosphere provided suitable heat conditions.Abundant water vapor condition was provided by the Plateau“wetland”and the water vapor channel that established by Southwesterly airstream.The position of air shaft in east plateau had a good indication of the heavy rain area and drop point.The area where Aba rainstorm occurred was just in left front of the southwest jet stream axis.