The Pinus sylvestris var. mongolica natural forest is mainly distributed in the Great Xing'an Mountains. To investigate different responses of radial growth of P. sylvestris var. mongolica to climate change in the southern and northern regions, we collected tree-ring samples from the southern and northern edges of the natural distribution of the forest. Tree-ring width residual chronology (RES) was developed using dendrochronological methods for each region. The relationship between tree-ring width and climate factors, including monthly mean temperature, monthly mean maximum temperature, monthly mean minimum temperature, monthly precipitation, and standardized precipitation evapotranspiration index (SPEI) from the previous October to September of the current year was analyzed by correlation analysis during the study period (1960-2013). The results indicated that tree-ring width was significantly positively correlated (r=0.639, P < 0.01) with average SPEI in April-September in the southern region (Arxan and Hailar), whereas it was significantly positively correlated (r=0.488, P < 0.01) with mean minimum temperature during the same period in the northern region (Mohe and Tahe). The southern trees suffered from water stress, whereas the northern trees suffered from low temperature stress. Thus, the southern tree radial growth was mainly limited by moisture from April to September, but northern tree growth was affected by the monthly mean minimum temperature of the same period. Radial growth exhibited consistently positive responses to precipitation, but the response was opposite for temperature from April to September (except June) in the two regions. Tree-ring width was basically negatively correlated with temperature in the southern area, and it was mainly positively correlated in the northern area. As temperature increased significantly in recent decades (P < 0.01), the sensitivity of radial growth of P. sylvestris var. mongolica to mean temperature during April to September increased, and tree radial growth showed an increasingly negative response to the mean maximum temperature from April to September in the southern region and an increasingly positive response to the mean minimum temperature in the northern region at 31-year intervals. In addition, temporal changes in growth patterns differed between the two regions over the past 54 years. Radial growth declined rapidly in the southern region (r=0.612, P < 0.001), whereas it increased significantly in the northern region (r=0.474, P < 0.001). The fitted linear regression showed that the rate of decline in basal area increment (BAI) was 0.253cm² /a in the southern area, and the rate of increase was 0.039cm² /a in the northern area. Further study determined that mean maximum temperature for April to September contributed most to southern tree growth variability from 1960 to 2013 (r=-0.681, P < 0.01). Hence, increasing drought stress caused by high temperature was the main reason for growth decline in the southern area. The northern BAI series tracked the standardized mean minimum temperature and precipitation series for April to September well. Rising minimum temperature benefited cambial cell activity and prolonged the tree grow period at high latitudes, and thus, increasing growth of northern trees was affected by both mean minimum temperature and precipitation. The warming climate restrains southern tree growth but promotes northern radial growth. If the warming is sustained, the distribution area of P. sylvestris var. mongolica may move northward in the future.