[OBJECTIVE] Cryogenic autolysis of Volvariella volvacea is an unusual phenomenon of abnormal metabolism. The aim of this study was to describe this molecular feature of abnormal metabolism at the genome-level. [METHODS] We used 21 fungal species for the phylogenomic analysis and then selected 9 representative species in basidiomycetes for the comparative genomic analysis. [ RESULTS] The phylogenomic analysis shows that V. volvacea was located at the bottom of the cluster consisting of grass-degrading fungi. Phylogenetic tree shows that basidiomycetes and ascomycetes fungi have independent evolutionary trajectories. Therefore, nine representative species in basidiomycetes were chosen for the comparative genomic analysis. The result shows that compared to other grass-degrading fungi, V. volvacea has the tendency of contraction. The comparison of the number of gene families on a different scale shows that there was a significant expansion of 3 large size ( > 200) gene families (faml, fam4 and fam6) in V. volvacea with their total number significantly more than other species, representing that the molecular feature of V. volvacea is correlated with its abnormal metabolism. [ CONCLUSION] The significant expansion of 3 gene families ( > 200) in V. volvacea indicates the enhancement of their function in specific gene families, which is most likely associated with cryogenic autolysis of V. volvacea.