Abstract: In mid-January 2008 ~mid-March, big snow disaster and freeze injure occur in Shiqu county, Ganzi prefecture, Sichuan province.Although this disaster occur under the background where low temperature, freezing rain and snow do damage in the whole nation range, but in many ways it has its particularity, in particular to have the local characteristic.In order to do a better job in the future, the author analyse the causes, effects and disaster prevention of the extreme disastrous weather and climate events carefully.The result indicates that the big intensity, long of duration, seriousness of the snow disaster are rare in the local meteorological records;atmospheric circulation anomalies, Ground frequent cold air activities, the West Pacific subtropical high northerly anomaly, the South-groove activities which caused by August 2007 to May 2008 the La Nina events are important reasons, and the local special geographical location and topography is another objective factors;Climate and weather forecasting, weather services and related departments synchronized with the disaster prevention minimize the losses caused by the disaster.