Abstract: In this study, the Picea purpurea community in Gahai-Zecha National Nature Reserve was taken as the research object, and the species composition and species diversity of each layer in the community were investigated and analyzed by community survey method. The results showed that: (1) There were 82 species of P. purpurea community in Gahai-Zecha National Nature Reserve, belonging to 41 families and 60 genera, which were dominated by Asteraceae, Rosaceae and Caprifoliaceae. (2) The richness index (S), Shannon-Wiener diversity index (H), Simpson dominance index (D) and Pielou evenness index (E) of each layer in the community were in the order of shrub layer > herb layer > tree layer. With the increase of altitude, the diversity indexes of tree layer and herb layer increased first and then decreased with the increase of altitude, and the diversity index of shrub layer decreased monotonically with the increase of altitude. (3) There was a negative correlation between altitude and diversity indexes of tree layer and shrub layer, a negative correlation between altitude and species richness index (S) of herb layer, and a positive correlation between altitude and other indexes of herb layer. The results showed that the species diversity of P. purpurea community in Gahai-Zecha Nature Reserve was greatly affected by altitude.