Many studies reported biotic change along a continental warming gradient. The temporal and spatial change of tree diversity and their sensitivity to climate warming might differ from region to region. however, understanding of the variation among studies with regard to the magnitude of such biotic changes is minimal, especially for montane ecosystems. To better understand spatial heterogeneity and temporal dynamics of mountain trees community change under climate warming over the past four decades. We re-surveyed and recorded all tree species from 107 long-term monitoring plots since 1974 in 2017 to study the changes of tree community composition of montane forests in the Giant Panda National Park. Our results showed that spatial differences were found in tree species diversity changes in response to climate warming over the past four decades. Tree species richness and abundance of montane forests increased over time in all our study area, except Liangshan (LS), especially in XiaoXiangLing with the highest warming rate. However, beta diversity underwent a significantly higher change rate at LS than in other mountains which indicated that plant species that do not belong to these four mountains entered LS in those year. Moreover, the beta diversities of tree between sample plots in the LS regions were homogenized. So, LS may become risk regions under continuing climatic warming, and should thus receive priority protection in the next conservation plan of the Giant Panda National Park (GPNP). We provide a explanation for the large variation among studies in warming-related biotic changes and recommend that the GPNP should implement a regional-specific conservation policy to strengthen conservation in at-risk regions (i.e., LS) under climate warming.