Abstract:Plant functional traits (PFTs) are plant attributes that can reflect plant life history processes, such as carbon acquisition, water transport and nutrient cycling, including plant features associated with plant physiology, morphology and phenology. Employing functional traits to answer questions regarding plant distribution, growth and survival, as well as to explore the mechanisms underlying plants' response to global climate change, remains a hot research topic in ecology over the past decades. However, it has been shown that trait-trait correlation and its association with environmental factors are rather variable or even reverse across ecological scales. The research progresses related to PFTs at different scales, i.e., within species, across species, across communities and across biomes globally were summarized. The limitations of current research of PFTs and proposed future research directions in this field were also discussed.