In order to explore the influence of climate change on the radial growth of Sabina squamata in the Source Region of Lancang River, samples of Sabina squamata were taken from Baqing County, Zaduo County, and Nangqian County in the Source Region of Lancang River, respectively. Dendrochronological method was used to measure the year-by-year tree ring width and basal area increment (BAI) of Sabina squamata in the three sample plots, and the standard chronology of Sabina squamata tree ring width was established and its response to climatic change was analyzed. The results showed that the annual mean temperature presented a rapid increasing trend from 1986 to 2019 in the Source Region of Lancang River (0.43℃/10a, P<0.01), and the annual mean minimum temperature (0.57℃/10a, P<0.01) increased significantly higher than the annual mean maximum temperature (0.33℃/10a, P<0.01), while the annual precipitation presented a weak upward trend (2.39 mm/a, P>0.10). Under the background of climate warming, the tree ring width of Sabina squamata showed an upward trend in the Source Region of Lancang River (P<0.01), and the growth rate of Sabina squamata ((0.37±0.16) mm/a) from 2000 to 2019 increased by 85% compared with that in 1986 to 1999 ((0.20±0.09) mm/a). The BAI also increased significantly, showing an upward trend ((12.16±5.16) mm²/a) from 1986 to 1999, and it was in a stable and rapid growth stage ((22.49±8.84) mm²/a) from 2000 to 2019, showing a stable and sustained growth ability. The correlation between the standard chronology of Sabina squamata tree ring width and climatic factors showed that the response of radial growth of Sabina squamata to temperature was significantly stronger than that of precipitation in the Source Region of Lancang River, which was not significantly positively correlated with precipitation in most months (June of last year to October of that year). However, it was significantly positively correlated with the temperature in most months. Compared with the monthly mean maximum temperature and mean temperature, the correlation between the radial growth of Sabina squamata and the monthly mean minimum temperature was more significant (P<0.01). Under the background of climate warming and humidification, the radial growth of Sabina squamata has entered a rapid growth period in the Source Region of Lancang River in recent 30 years, and the tree ring width and BAI were characterized by rapid growth, indicating that the climatic conditions in this area were more suitable for the growth of Sabina squamata.