A continuous severe rain occurred on 2 November 2008 in Chuxiong，Yunnan Province，which initiated an exceptional big geological disaster and created a huge loss of life and property. By means of the data of MICAPS 3， conventional meteorological rainfall， intensive unattended station rainfall， and satellite cloud pictures， the meteorological causes of the event are analyzed.The results indicate that besides natural causes such as geological condition and landform，the historically rarely seen severe rainfall is a major trigger.The direct factors of the event include the mesoscale convergence weather system， abundant watervapor transport and convergence， upperlevel and lowerlevel jets， and lowermid level shear.