Abstract: The occurrence and development causes of a severe rainfall weather process that happened in Hexigten Banner from June 5th to 7th 2014was revealed in this article. The results showed that upper-level low vortex was the main influence system for this weather process, Blocking function of Okhotsk Sea blocking high made the system move slowly and last for a long time, The invasion of upper dry cold air and the coupling of upper and lower jets provided abundant moisture and strong ascending motion for this rainfall process.