Based on the regional chronology established by the four ring-width standard chronologies of Sarcozygium xanthoxylonin the middle of Alashan Desert,we studied the response of Sarcozygium xanthoxylonradial growth to climate change and the wet/dry variation recorded by regional chronology.The results showed that the radial growth of Sarcozygium xanthoxylon was mainly affected by the pre-growing and growing season precipitation(October-December in previous year and April-July in current year).On the interdecadal scale,three dry periods were identified in the middle of Alashan Desert:the early 1920s to early 1930s,the early 1940s,the late 1970s to late 1980s;Four wet periods were the late 1900s to early 1920s, 1930s,the mid-1960s to mid-1970s,the late 1980s to the present.According to the results of wavelet analysis, the regional chronology in the middle of Alashan Desert had significant period cycles of 2-8 a,11 a and 16-34 a,and the periodic oscillation occurred at the end of 1970s.These results could provide climate change information and decision-making basis for regional environmental evolution and desertification control.