The slope aspect is one of the most critical topographic factors in mountainous areas. Little is known, however, about the effect of the aspect on the ectomycorrhizal (ECM) fungal community. Additionally, we know very little about the composition of ECM fungal communities associated with Quercus variabilis, which is widely distributed in East Asia. In this study, we compared the richness, community composition, and exploration types of ECM fungi associated with Q. variabilis between predominantly south- and north-facing slopes in the Taihang Mountain, North China for the first time. DNA was extracted from the root tips of Q. variabilis, and Illumina MiSeq sequencing was used to identify ECM fungi. In total, 168 operational taxonomic units belonging to 28 genera were detected, and the ECM community was found to be dominated by Russula, Inocybe, Tomentella, Scleroderma, and Cortinarius. Compared with the north-facing slopes, the ECM communities on the south-facing slopes had higher diversity. The community composition and exploration types were directly affected by the slope aspect. Also, the aspect-induced edaphic variables, such as total phosphorus, total nitrogen, total potassium, pH, and soil water content, were important sources of variation in ECM fungal richness and distributions of exploration types. Different genera tended to be distributed in various slope aspects. Cenococcum, Genea, and Clavulina were significantly enriched in north-facing slopes, while Geopora, Helvelosebacina, Scleroderma, Gyroporus, Astraeus, Boletus, Tricholoma, Hebeloma, Cortinarius and unclassified Thelephoraceae were more abundant in south-facing slopes. Hydrophobic ECM fungi were obviously enriched in the south-facing slope, but there was no statistical difference between hydrophilic among the south- and north-facing slopes. Our study deepened our knowledge of the aspect-driven variation in ECM fungal communities associated with Q. variabilis.