Abstract: Plant leaves represent an important interface between a plant and the surrounding environment, and their functional traits are influenced by the external environment and phylogeny. Elucidating variations in leaf functional traits in different environments is crucial to understand plant adaptation. In this paper, the types and functional significance of the functional traits of leaves are summarized. Related studies on the two main factors affecting the functional traits of leaves (environmental factors and phylogenetic history), as well as involvement in plant adaptation, are also discussed. Finally, we propose prospective research directions based on the current situation and future tendency of leaf functional trait studies.