By using conventional meteorological observation data, satellite data, NCEP FNL reanalysis data, the severe rainstorm process which happened on 14 June, 2011 in northern Jiangxi was analyzed in this paper. The results show that: (1) The severe rainstorm over Meiyu front happens in extremely favorable weather situations and frontogenesis and terrain result in the vigorous development of meso β scale system. (2) With stable circulations, cold air flow behind the 500 hPa trough stands facing the warm and wet flow in south, continuously, causing to the rainstorm maintain over the northern part of Jiangxi. The favourable ambient field for this event is formed by strong thermal instability, strong vertical wind sheer, plentiful water supply in low level and strong convergent lifting.(3) Co operation between multi scale systems makes extremely strong southwest jet and the strong ascending motion, strong divergence in higher levels, strong convergence in lower levels are coupled with the development of meso scale system. All of these factors trigger the rainstorm happen on the Meiyu front. The positive vorticity develops upward along the front area of θse, which enhances convective ascending motion and releases lots of instable energy. (4) Main precipitation core located in northeast Jiangxi is due to the joining of air flows in different levels and the interaction between convergence at boundary layer and trumpet shaped terrain.