The response of species diversity to elevation gradients is a hot topic in ecological research under global climate change. The objective of this study is to investigate the variation of plant community species diversity along the elevation gradient in the Baishanzu Park Area of Qianjiangyuan-Baishanzu National Park (hereinafter referred to as Baishanzu National Park). The study adopted the transect method and set up a group of three continuous elevation gradient transects in Baishanzu National Park. Continuous vertical transects had more advantages than discontinuous elevation distribution. With more accurate detection capabilities and more sensitive detection methods, we could better study the changes and mechanisms of species, community and biodiversity at any altitude. The three transect-zones covered typical ecosystem types at various elevations in the park, while avoiding areas with frequent human and animal activities and areas with unstable soil matrix. In order to facilitate long-term monitoring in the future, the transshipment was constructed in accordance with domestic and foreign norms of forest dynamic monitoring sampling survey. The bandwidth of the constructed sample was 30 m, the total length was 3210 m, the elevation was 636.3 m to 1928.04 m, and the total area was 9.63 hm². The responses of α and β diversity of plant communities to the elevation gradient were analyzed through the species names and diameter at breast height (DBH) of all woody plants ≥ 1 cm in the transect. The results showed that a total of 69914 individuals of woody plants belonging to 260 species, 109 genera, and 55 families were recorded in the three transects. Species richness, Shannon-Wiener diversity index, Simpson dominance index and Pielou evenness index were negatively correlated with elevation. Among topographic factors, elevation had the greatest effect on α diversity, followed by slope, and aspect had little effect on α diversity. The Jaccard similarity index was significantly negatively correlated with the elevation distance between sample plots, that is, the Jaccard similarity index of the community decreased with the increase in the elevation distance between sample plots, while β diversity was significantly correlated with elevation, slope and aspect, in which elevation had the greatest effect, followed by slope, and aspect had little effect. The turnover component of species β diversity (Jaccard dissimilarity index) was larger than the nested component on the elevation gradient, that is, the turnover component was dominant on the elevation gradient, and the differences in species composition among plant communities were controlled by species replacement. The results provide a scientific basis for the future policy formulation of biodiversity conservation and stability maintenance of mountain ecosystems in Baishanzu National Park and other subtropical mountainous areas.