Abstract: In order to explore the species diversity of Larix principis-rupprechtii forests in Shanxi Province of northern China, 40 typical sample plots of Larix principis-rupprechtii forests were investigated from the field. Based on the result of TWINSPAN classification, the communities were classified into 10 associations. The species diversity of Larix principis-rupprechtii communities in Shanxi was studied by species richness index (R), Simpson index (D), Shannon-Wiener index (H′) and Pielou evenness index (E). Through this study, it is hopeful to provide scientific basis for protection and rational exploitation of Larix principis-rupprechtii communities. Community H′ index was affected by R and E indexes together, containing more information about community composition structure and distribution condition. The results indicated that the rank of species richness index for ten associations was association 2>association 1>association 3>association 9>association 4>association 5>association 10>association 6>association 7>association 8. All Larix principis-rupprechtii associations had higher species diversity index, and it had big difference in the different associations. It showed that the Larix principis-rupprechtii communities had more complex structure, higher organization level and appropriate growth environment. The biodiversity index was the highest in herb layer, followed by the shrub layer and the forest layer, which suggested that the herb layer contributed to the overall community richness mostly. The results of one-way ANOVA for those indices among 10 associations showed that R had a significant difference (P < 0.05), and H′ had extremely significant difference (P < 0.01), while the difference between D and E was not significant (P>0.05).