Elevational patterns of species richness and their underlying mechanism have long been one of significant issues in macroecology. Species richness along the elevation gradients shows four patterns, the common pattern of which is unimodel with mid-elevation peak. Multiple hypotheses were proposed to explain the patterns,including four aspects: climate,spatial effect, interaction among species, and evolutional history. These hypotheses were used to explain the species richness elevational patterns from different aspects. This article reviewed the history of research on elevational pattern of species richness,the methodology and the potential mechanisms for elevation patterns. These hypotheses mainly included water-energy dynamic hypothesis, metabolic theory of biodiversity,productivity hypothesis,relationship between species and area,middomain effect, habitat heterogeneity and static evolutionary models. The review introduced the distributional pattern of species richness along elevation gradient and the ecological evolution process affecting the pattern. At present, most of studies focused on the role of modern climate, but the parameters used as modern climate were so strongly collinear with each other that it was difficult to distinguish the absolute contribution of certain climate factor. Combined modern climate with phylogenetic analysis, the phylogenetic characters of species in different elevational bands were compared to help to further understand the elevation patterns of species richness, their underlying mechanisms and effect of modern climate fluctuation on vegetation community.