Abstract: Based on the February averagetemperature data from 1961 to 2009 of Yunnan and the abnormal index,we analyzed the space distribution,the history rank and the anomaly cold and warm tendency of the disaster events that induced by the extreme low-temperature,the sleet and the frost in 2008 and the extreme high-temperature dry in 2009.Besides,we analyzed the cause of the disaster events by using the NCEP/NCARreanalysis data.The results show that within meteorological phenomena records,it was the coldest year in the past 40 years in early spring of 2008,but the warmest year was in early spring of 2009.The eastern averagetemperature in early spring in Yunnan tends to warm sincethe eighties of the 20 th century and the warm extremely phenomenon was fairly outstanding since 2000.Analyzing the reasons of the disaster events,we believed that there was a prominent difference in the circulation field of mid and high latitude in Northern Hemisphere in February of 2008 and 2009.The height departure distribution was '+-+' on 500 hPa in eastern Asia in February of 2008,but '-+-' in February of 2009.The direct reason of the extreme low-temperature,the sleet and the frost was that Ural Mountains blocking high and southern branch trough was exceptionally stronger,and the cold air activity was frequent,which gave riseto the continual low-temperature and accumulative precipitation in early spring of 2008.The another direct reason of the unusual high-temperature in early spring of 2009 was that Ural Mountains blocking high was exceptionally weaker than normal,as well as East Asia trough and the cold air activity were more eastward,which leaded to the few precipitation in Yunnan.