Abstract: The integrate freezing damage index(IFDX)of Korla fragrant pear trees was established based on the daily temperature data at Korla weather station from 1959 to 2011,including extreme minimum temperatures in winter,minimum accumulated temperatures of average T≤-10℃, of daily average temperatures in winter and the days with min T≤-15℃,by using the principal component analysis,the IFDX feature was analyzed by using linear regression,M-K test and .Morlet wavelet.The results showed that the bigger IFDX was,the more serious damage,and pear trees reached the critical index when IFDX≥1.0.There was no obvious linear change in the IFDX in last 52 years,but there was a dramatically reduction around 1979.The decadal change in IFDX was clearly characterized by the periodic signal 32 to 38 years,and there was a near 9 years decadal cycle before 2000,which shortened after 2000 and changed into a 3 to 4 years sub cycle in the resent 10 years.The results could provide direction for Korla fragrant pear tree freezing damage monitoring and warning.

Key words: Korla fragrant pear trees, Integrate freezing damage index, Freezing damage