Global warming has a strong effect on plant traits at high latitudes and high altitudes. To explore plant adaptability to global warming,more ecologists focus on the responses of leaf traits to warming,because the leaf is the key photosynthetic organs and sensitive to climat change. Previous studies have proved that warming directly influenced the plant leaf area, leaf life, phenology, and lateral growth. More evidence has shown that the responses of leaf traits to warming is Highly species-specific. However, none of these studies included specific leaf traits or focused on the effects of long-term warming. In generally, different leaf traits respond differently to simulated warming, and these provide insights into how key plant speceis adapt to climate change. Abies faxoniana is one of the important woody species in subalpine coniferous forests. Could A. faxoniana expand to a higher altitude region (e.g. treeline ecotone) in the future climate warming scenario? Therefore, we used in situ open-top chambers to simulate warming and study the long-term effects of warming on leaf traits (leaf length,leaf width,and leaf thickness) and leaf plasticity at different ages (annual,biennial, and triennial) of A. faxoniana seedlings. The goals of this study were to determine how A. faxoniana changed their leaf traits and corresponding plasticity under simulated warming conditions. The results showed that simulated warming had a negative effect on the length, width, volume, and area of needles (reduced 12.77%, 11.86%, 11.49%, and 17.76%, respectively) , whereas simulated warming had a positive effect on leaf thickness (increased 7.27%, P<0.05 ) . The responses of leaf traits to simulated warming had a significant differences in the age (P < 0.05). Combined the effects of simulated warming and leaf age, leaf length, and leaf area had been changed significantly (P < 0.05) , whereas the reponses of leaf width and leaf thickness to simulated warning were the opposite. Phenotypic plasticity index (PPI) and coefficient of variation (CV) showed that simulated warming promoted the plasticity of leaf traits, leaf length of the annual leaves excepted. However, there were significant inter-annual differences in the effects of warming on leaves of different ages. In summary, the present study suggests that A. faxoniana seedlings leaves could adapt to global warming via regulating leaf traits to enhance its plasticity.