Abstract: Relationship between biodiversity and ecosystem functioning is the present focus of ecological research,functional diversity is the best predictor of ecosystem functioning to determine the intensity and form in the relationship between biodiversity and ecosystem functioning.In this article,based on the review of the great deal of scientific literatures,the definition of functional diversity and its study methods were introduced,and the application of each functional diversity index was also compared.The relationship between functional diversity and the important index of traditional biodiversity:species richness and its factors,the relationship between functional diversity and ecosystem functioning and its factors were argued.Meanwhile,the application of functional diversity in ecosystem management practice,and the research trend of functional diversity were discussed.