Abstract: In order to study the characteristics of severe short-term precipitation in Hunlun Buir and to guard against the impact on agriculture from flood disasters caused by severe short- term precipitation, using automatic meteorogical observing data, NCEP reanalysis data and satellite images, the causes of a severe shortterm precipitation occurred in Hulun Buir on 12 July 2009 were preliminarily studied. The results showed that: upper forward trough provided favorable large scale condition for the severe short- term precipitation, it occurred on coincidence area between the convergence by warm shear line in low level and the divergence by weak ridge in high level , appeared inflow boundary of the development stage of MCC. The atmosphere feature of the severe short- term precipitation exhibited strong convective instability of higher humidity and higher temperature in low level, strengthen vertical wind shear, ascending motion and positive helicity. The convective instability was released by the invasion of dry air in the middle troposphere, that caused the severe short-term precipitation.