As a component of biodiversity, plant functional diversity is considered a key factor in understanding the link between ecosystem functioning and biodiversity. In this study, we researched the functional diversity of the Ulmus lamellosa community in the Taiyue Mountain area of Shanxi. We investigated 11 traits, including habitat type, spread of seeds, pollination, type of nitrogen fixation, life history, life form, leaf type, plant height, coverage, flowering period and flowering time. The functional diversity of 7 U. lamellosa associations and the elevation pattern were analyzed by using FAD, Rao’s, SL and CL indices. Results showed that, the FAD, SL, CL indices decreased from association I to VII, and the Rao’s indices increased, and both implied the functional diversity decreased in this order. Regression models indicated that elevation was the primary determinant of the functional diversity, and functional diversity decreased with increasing elevation.