Abstract: The strong convection weather is the high frequency disastrous weather in summer in Hulun Buir.Thunderstorms and strong rainfall happens from time to time.Conventional weather chart,automatic weather station encrypted precipitation observation data and radiosonde data was used to analyse strong precipitation process of Hulun Buir city central area from July 25th 2011 08 to July 26th 08.The results show that： firstly,low-level jet brought warm and moist air of the Sea of Japan and the East China Sea into the city.Secondly,with the wind speed and direction changing on the left side of the low-level jet,a low pressure formed and developed.It caused strong ascending motion on the left side of the jet axis.Thirdly,the cold northwest wind brought by the westerly trough conjuncted with moist air.It led to the formation of unstable stratification and offered the most favorable weather conditions for the storm.