Abstract: On the basis of the daily radiosounding data collected from twelve stations in Xinjiang from 1960 to 1999, it was divided into four regions by climate features: the Altai Mountains, the northern and southern slopes of Tianshan Mountains and the Kunlun Mountains. The change trend of average height and difference in the spatial distribution of the first tropopause for 40 years were analyzed, and the test of abrupt change was conducted by means of Mann-Kendall and running t-test. The results show that there was an increasing trend of average height for the first tropopause over Xinjiang as a whole during the period from 1987 to 1999 in particular. From the view of the interdecadal change, it obviously decreased from 1960s to early 1970s and then has gradually increased since 1970s.The running t-test shows that a remarkable mean change occurred in the Altai Mountains in 1972, the southern slope of Tianshan Mountains in 1976 and the northern one in 1979, but there was no abnormal change in the Kunlun Mountains. The average height obviously increased all over Xinjiang with the exception of Kunlun Mountains. Although there were all kinds of differences in various regions, the increasing trend was rather similar from the end of 1980s to 1999 over Xinjiang.

Key words: the first tropopause height, change trend, analysis of abrupt change