Wood-decaying fungi decompose cellulose, semicellulose and lignin in wood by exuding various hydrolytic enzymes, so they play an important role in substance cycling in forest ecosystems. A field investigation to study these fungi was carried out in a permanent plot in the Fenglin National Nature Reserve. The wood-decaying fungal species, abundance and host wood characters were recorded. We analyzed the relationship between fungal diversity and the characters of the host wood, including species, abundance, degree of woody decay and wood diameter. A total of 295 specimens identified as 93 wood-decaying fungal species were recorded. The Shannon index was 3.86, and the Simpson index was 0.96. The species richness and abundance of wood-decaying fungi was significantly correlated with wood diameters of 2–5 cm and 5–10 cm, with a classification of 2 in degree of decay and with pine wood. The dominant hosts were Acer, Corylus, Picea and Pinus, and they each hosted different fungal communities. The dominant fungi in maple and hazelnut wood were Daedaleopsis tricolor, Trametes versicolor and Trichaptum pargamenum. Irpex lacteus, Trametes versicolor, Trichaptum abietinum and T. fuscoviolaceum were the dominant fungal species in pine and spruce wood. The analysis of the growing probability of fungal basidiocarps showed that the ratio of wood with basidiocarps to all dead wood of the same species plateaued in areas up to 0.36 ha. For example, the ratio of pine wood with basidiocarps to all pine wood was 10.2%, the ratio was 12.9% for maple wood, the ratio was 13.4% for spruce wood, and the ratio was 53.7% for hazelnut wood. These findings can help predict the occurrence of certain wood-decaying fungi in forest ecosystems.