Abstract: Changnienia amoena Chien is a monotypic species and endemic to China.In our experiment,microstructure of mycorrhiza and fungal species of Changnienia amoena were studied.Observations on the microstructure of mycorrhiza of wild Changnienia amoena demonstrate that it has the typical mycorrhizal structure of orchids.Mycorrhizal fungi enter the velamen and exodermis through root hair,invade the cortical tissue by the exodermal passage cells and then form pelotons.Isolation has been carried out twice and 36 strains have been isolated.These belong to the Classes Basidiomycotina and Deuteromycotina;of these,the superior genus is Fusarium.Sixteen fungus strains were inoculated to tissue-cultured seedlings of Dendrobium sinense and 10 of them promoted the growth of seedlings at different levels after inoculation.The average height increment of the seedlings inoculated with strain(DHL-19) is significantly higher than that of the control(α=0.05) and the average height increment of the seedlings inoculated with two fungus strains(DHL-16 and DHL-17) is also significantly higher than that of the control(α=0.01).The primal strains were re-isolated and a few pelotons were observed from the three treated seedlings.We conclude that DHL-16,DHL-17 and DHL-19 should be used as the mycorrhizal fungi for orchids.