Abstract: Plants are closely related to the microorganisms in their growing environment, they affect and depend on each other. In order to explore the changes of the bacterial community in the phyllosphere of Arundinaria spanostachya in different seasons, the composition and diversity of phyllosphere bacteria of A. spanostachya in Sichuan Liziping National Nature Reserve were analyzed by high-throughput sequencing technique. The results showed that Proteobacteria phylum was dominant in the phyllosphere of A. spanostachya. The relative abundance of Acidobacteriota bacteria of A. spanostachya in spring was significantly higher than that in autumn, while the opposite trend was found for Proteobacteria bacteria. In spring, the relative abundance of 1174-901-12 and Granulicella was significantly higher than that in autumn, while the opposite trend was found for Sphingomonas and Mucilaginibacter. The Sobs index and Shannon index of phyllosphere bacteria of A. spanostachya in autumn were significantly higher than those in spring. Based on the principal coordinate analysis of weighted-unifrac distance and unweighted-unifrac distance, it was found that there were significant difference in the community structure of phyllosphere bacteria of A. spanostachya in spring and autumn. The dominant Proteobacteria bacteria had a potential impact on maintaining the intestinal health of giant pandas in this mountain range. The plant beneficial Sphingomonas and Pseudomonas bacteria were also beneficial to the health and growth of this bamboo species. The results are helpful to understand the difference of bacteria diversity and community structure of phyllosphere bacteria of A. spanostachya in Xiaoxiangling Mountains, which could provide reference for the management and conservation of giant pandas’ staple food bamboo.