All orchids have an obligate relationship with mycorrhizal symbionts during seed germination under field conditions, and in many species, the dependency on fungi as a carbohydrate source is prolonged into adulthood. Diversity of orchid mycorrhiza is defined as the species of mycorrhizal fungi compatible with an orchid and the shape of compatibility links between orchids and fungi are referred to as webs. According to traditional records, the majority of mycobiont in terrestrial orchid mycorrhiza belonged in several certain taxonomic groups of basidiomycetes, and there were specific relationships between orchids and fungi. Subsequent studies indicate a more complex situation. The factors which influence the diversity of orchid mycorrhizal fungi is not exactly known. Trophic styles, geographical differences, environmental conditions, or life stages have been reported to play a role in the fungal diversity. Considering the huge temperate zone and alpine mountains, China has rich terrestrial orchid resources. The Huanglong Valley in Sichuan Province, at an elevation of 3100-3569 meter and 3.5kilometers long, is the largest travertine region in the world. Profuse terrestrial orchids from 30 species in 19 genera were found in this narrow valley. Huanglong Valley is one of the temperate terrestrial orchid distribution centers in China. These orchids grew in two different habitats. One was open shrubs with travertine stream flows; another was relative dense mixed coniferous broad-leaved forests without water flows. Cypripedium flavum, Galearis diantha, Ponerorchis chusua and Phaius delavayi were the main orchid species found in open shrub habitat with abundant individuals. Tipularia szechuanica, Platanthera minutiflora, Corallorhiza trifida and Neottia acuminata were the dominant orchid species in forest habitat, the latter two species were myco-heterotrophic, which rely on mycorrhizal fungi throughout their lifetime. From a conservation perspective, this study investigated the diversity of mycorrhizal fungi of temperat wild orchids in the Huanglong Valley, and whether the fungal diversity would vary between different growing periods of orchids, and with the species of host orchids from different habitat. Samples were taken in the different seasons over one year. The mycorrhizal fungi were isolated in tissue blocks cultivation, and identified by using micro structure examination and ITS gene sequence analysis methods. We investigated the diversity of mycorrhizal fungi with species number and Simpson′s diversity index. The phylogenetic diversity of fungi isolates was also investigated. Forty-one fungi species were isolated from the samples. It was very rare for the eight orchids to share similar species during the same growing period. The molecular phylogeny indicated that the fungi mainly belonged to Helotiales and Hypocreales of Ascomycota, and Tulasnella of Basidiomycota. The Ascomycota was dominant, containing 35 species. Mycorrhizal fungi specificity at the species level was not been found except for Galearis diantha, which was associated with only Hypocrea fungi through out the whole growing season. Species number and Simpson diversity index (D) of mycorrhizal fungi from the orchids growing in a forest habitat were higher than those in a travertine habitat. The variation patterns of mycorrhizal fungi diversity from both habitats were synchronized with the season changing pattern of the Huanglong Vally. The peak of mycorrhizal fungi diversity appeared in the vegetative period, and the minimum value was in the fruiting period. Moreover, the changing pattern of the mycorrhizal fungi diversity between different growing periods was closely associated with the nutrition requirement of the orchids during different growing stages.