Functional diversity has been a hot topic in biodiversity research in recent years.addresses a wide range of important ecological questions while linking species and ecosystems through mechanisms such as complementary resource use and mutualism. Understanding plant functional diversity as a component of biodiversity is important understanding the link between ecosystem function and biodiversity. However, the concept itself remains rather ambiguous because of questions that remain related to defining, measuring, and assessing the performance of functional diversity. In view of the extensive literature on this topic, we systematically define functional diversity and subsequently introduce and compare six methods of measuring functional diversity. We selected 13 functional traits of various species: seed dispersal, pollination methods, plant height, coverage, vegetation type (such as herb, shrub, or tree), leaf shape, blade hardness, length of the flowering period, flowering period, fruit type, fruit shape, fruit ripening period, vegetation was stabbed. We used measures of thse traits to calculate six functional diversity indices: functional attribute diversity, modified functional attribute diversity, convex hull hyper-volume, functional evenness, quadratic entropy, and functional dispersion, combined with a community species richness indexthe Shannon-Wiener index and a species evenness index. unctional diversity of tree and shrub layers studied in the Wulu Mountains National Nature Reserve in Shanxi, China. The study had two goals: to explore the relationship between species and functional diversity and to analyze characteristics of currently used functional diversity indices. unctional attribute diversity, modified functional attribute diversity and convex hull hyper-volume were positively correlated with species abundance and the Shannon-Wiener Index. Functional evenness was positively correlated with the Shannon-Wiener and species evenness indices. Quadratic entropy and functional dispersion were positively correlated with species evenness and Shannon-Wiener indices. We measured the functional diversity of forest communities in the Wulu Mountains Nature Reserve in Shanxi using the six functional diversity indices. We found that functional diversity is an increasing function of species richness and diversity.differences functional diversity were largely affected by differences in the 13 selected functional traits. Vegetation differed among communities reflecting variations among communities. Species abundance varied among communities, indicating that any variation in species leads to differences among communities. sing both Pearson correlation and principal component analysis (PCA), indices of functional diversity be divided into three main categories, each corresponding to a single aspect of functional diversity: functional richness (functional attribute diversity, modified functional attribute diversity, convex hull hyper-volume), functional evenness, and functional divergence (quadratic entropy functional dispersions). Each index reflected the definition of its properties, the different aspects of functional diversity independent each other. The results indicated all of these indices are significantly correlated with each other. these functional diversity indices provide effective measures functional diversity. In practical research, we propose researchers should use several indices simultaneously to evaluate functional diversity. Thus, research related to community functional diversity of the Wulu Mountains Nature Reserve significant vegetation recovery and protection because understanding functional diversity will allow land managers to protect and recover degraded communities.