[Objective] Coevolution and mutualism have existed between endophytic fungi and tea plants for a long time. They play an important protective role in the ecosystem of biotic and abiotic stress. Their community structure composition is relatively stable and has certain changes under the influence of external factors, but the effect of biotic stress on endophytic fungi community structure of tea leaves is still lack of systematic research. Therefore, it is necessary to study the diversity of endophytic fungi community structure under biotic stress.[Methods] We sequenced the ITS1 region of ITS rRNA genes of endophytic fungi in tea leaves of the diseased group and healthy group by high-throughput sequencing technology, and the microbiota composition and diversity were compared and analyzed.[Results] The results showed that the diseased group had lower endophytic fungal diversity and microbial community richness than those of the healthy group. At the phylum level, Ascomycota was dominant in both of them. At the genus level, Colletotrichum and Pseudopestalotiopsis were dominant in diseased group samples, Cladosporium was dominant in healthy group samples. In addition, there were significant differences in community structure composition of endophytic fungi between the two groups. The relative abundance of Pseudopestalotiopsis, Colletotrichum and Arthrinium in diseased group was significantly higher than that of the healthy group. However, the relative abundance of Mortierella, Aspergillus, Plectosphaerella, Lectera, Botryotrichum, Penicillium, Gibberella, Chaetomium, Lulwoana and Verticillium in diseased group were significantly lower than that of the healthy group.[Conclusion] The occurrence of tea grey blight changed the community structure of endophytic fungi in tea leaves and made a few species grow preferentially. These results provide insights into the effect of fungal diseases on the endophytic fungal community structure of tea leaves, and also lay the foundation for the pathogenic mechanism of the pathogen and provide the theoretical basis for the prevention and control of tea plant diseases.