Wood-inhabiting fungi are one of the most important parts of forest ecosystem, and play an important role in degrading the wood in forest ecosystem. The major species of these fungi include the groups of Aphyllophorales (Basidiomycota), Discomycetes (Ascomycota) and some imperfect fungi. They have the ability to degrade cellulose, hemicelluloses and lignin of wood. Three type of wood decaying have been found, i.e., white rot, brown rot and soft rot. Many other organisms of forest ecosystem have symbiosis relationship with wood-decaying fungi. Wood-inhabiting fungi could offer the nutrition for many insects and birds, and spores of many wood-rotting species are spread by some insects. The high biodiversity of wood-decaying fungi is one of the important factors for the health of forest ecosystem.