Abstract: Understanding the growth dynamics of tree xylem in arid and semi-arid areas of China and its response to climatic factors is crucial for assessing and predicting forest productivity and carbon sequestration potential under climate change. In this study, the intra-annual xylem formation of four Quercus mongolica in Liupan Mountain Nature Reserve of Ningxia were monitored by micro-core sampling technique in two growing seasons（2019 and 2020）, and mixed linear model was used to explore the effects of temperature and precipitation on xylem growth rates. The results showed that there was no significant difference in intra-annual xylem formation dynamics between the two years（P＞0.05）. The onset of xylem formation started from early April and ceased from mid-to-late September, resulting in a growing season length of（177±17） days（2019） and（165±24） days（2020）. The results of the mixed linear model showed that the annual xylem growth rate of Q.mongolica was positively correlated with the maximum, mean, minimum temperatures, as well as total precipitation in the preceding 7, 10 and 15 days（P＜0.01）. Under global change, the xylem growth of Q.mongolica may benefit from future warm and humid climate conditions in Liupan Mountain Nature Reserve, Ningxia.