Investigating the functional traits and construction costs of leaves in endangered plants is crucial for understanding their adaptive strategies,deciphering endangerment mechanisms,and formulating effective conservation measures.We systematically examined the functional traits including leaf fresh weight,dry weight,length,area,specific leaf area,dry matter content,and nitrogen content,and construction costs of mature leaves from different leaf positions (upper,middle,lower) in adult Terminalia myriocapra trees in Simao district,Pu’er,aiming to elucidate their resource use strategies and adaptation mechanisms at the leaf level.The results showed that:1) Significant differences were found in functional traits among leaf positions,with the middle leaves exhibiting the highest values in fresh weight,dry weight,length,and area,followed by upper and lower leaves.2) Significant correlations were observed among leaf functional traits,indicating synergistic and trade-off relationships.3) The construction cost per unit mass was positively correlated with leaf fresh weight,dry matter content,and nitrogen content,but negatively correlated with specific leaf area.4) By the principal component analysis,the lower leaves tend towards a conservative resource-use strategy,middle leaves towards an acquisitive strategy,and upper leaves represent an intermediate strategy.The results systematically revealed the differentiation of functional traits and allocation strategies of construction costs across leaf positions in T.myriocapra,providing new evidence at the leaf level for understanding its ecological adaptation and endangerment mechanisms,and offering a theoretical basis for the conservation and sustainable utilization of T.myriocapra.