Municipal solid waste landfill is the main disposal option for domestic garbage, in which microbial activities play an important role. However, despite the widespread practice of landfilling, the metagenomic microbial profiles of landfill sites remain poorly characterized. In this study, we used a combination of physicochemical analyses, UV-visible spectrophotometry, and high-throughput Illumina shotgun sequencing to systematically investigate the changes in soil enzymatic activities, microbial community structure, and functional attributes in aged refuse from the XinGou municipal solid waste landfill in Taiyuan, China. With the exception of neutral phosphatase (P = 0.065), the activities of urease, laccase, dehydrogenase, sucrase, neutral protease, and β-glucosidase were all markedly reduced in aged refuse compared with the control soil (P < 0.05) Contrastingly, catalase activity was found to be significantly elevated in the aged refuse. Aged refuse was characterized by a higher richness and diversity of microbial communities, as reflected by the higher values of community richness estimators (Chao1 and ACE) and diversity indices (Shannon and Simpson). In total, 186 phyla, 4 354 genera, and 34 459 microbial species were identified. Of these, 132 phyla, 1 914 genera, and 7 369 species showed significantly different abundances in the aged refuse compared with the control soil. Actinobacteria and Acidobacteria were identified as the dominant phyla in the control soil, whereas Proteobacteria, Euryarchaeota (Archaea), and Firmicutes were found to predominate in the aged refuse. Notably, Euryarchaeota and Methanoculleus were the major taxa detected in aged refuse, although were almost completely absent from the control soil. Xenobiotic biodegradation and bacterial chemotaxis were the main functions of the microflora in the aged refuse, whereas the carbohydrate, amino acid, energy, and lipid metabolism pathways were significantly enriched in the control soil. Moreover, the aged refuse contained a high abundance of genes involved in quorum sensing. Our findings in this study revealed close associations between enzyme activities and variations in the microbial community structure and genes that are actively involved in biodegradation activities at landfill sites. This is the first study to examine the metagenome of the Xin Gou municipal solid waste landfill, and our findings indicate the landfill environment is characterized by a more complex spectrum of microbial activities than expected. Further investigations are needed to gain a more comprehensive understanding of the microbial community structure and functional attributes, as well as their potential influencing factors in landfills.