Background On the one hand, Armillaria is regarded as a plant disease that causes serious root rot of forest trees, on the other hand, Armillaria is also an important symbiotic fungi of the valuable Chinese herb Gastrodiaelata. Currently, the whole genome database of Armillaria is relatively limited, and it is expected that a more comprehensive understanding of the symbiotic interactions between Armillaria and G. elata can be achieved through genome-wide comparisons and functional annotations. Whole genome sequencing of Armillaria gallica M3 strain was performed using Oxford Nanopore Technologies sequencing platform, and the sequencing data were used to perform genome assembly, gene prediction and functional annotation, carbohydrate-active enzymes, and host-pathogen interactions using bioinformatics methods. Results In this study, we obtained an 83.33 M genome of A. gallica M3 strain, which consisted of 38 overlapping clusters with an N50 of 6,065,498 bp and a GC content of 47.43%. A total of 12,557 genes were identified in the genome of A. gallica M3, and the repetitive sequences accounted for about 44.36% of the genome. 42.26% of the genome was composed of glycoside hydrolases (GHs), 16.15% of the genome was composed of glycosyltransferases (GTs). In addition, 3412 genes in A. gallica M3 were involved in the host-pathogen interaction mechanism. results have elucidated the characteristics of A. gallica M3 from a genomic perspective to a certain extent. They help to analyze the inner mechanism of A. gallica M3 being able to symbiosis with G. elata at the genomic level, which is of great significance to the next related research of A. gallica M3.