Abstract: The Auricularia auricularia strain ‘Shen 8-9’ was used as test material, the study on the response of Auricularia auricularia germplasm to high temperature stress was carried out by measuring the MDA content and activities of SOD,PPO,CAT and GR of hypha, though observing the growth rate, growth potential and microscopic morphology of hypha after different time of high temperature stress and after resuming culture for a period of time, in order to provide reference for reasonable control of environmental conditions, and the selection of varieties resistant to high temperature.The results showed that there were changes in oxidative damage degree, colony morphology and mycelial micromorphology of black fungus cultivars to high temperature stress at different times.With the prolongation of stress time, the content of MDA and the activities of SOD,PPO and CAT in mycelia were significantly different, while the activity of GR was not significantly changed.In the general scenario, colony hypha and growth potential were as follows, the growth rate of hypha gradually decreased, and the hypha at the colony edge became yellow, sparse, and atrophied seriously with the extension of stress time.The optical micromorphology was as follows, a large amount of melanin was produced in hypha, some tip hypha twisted into clusters, some hypha broke and had diamond, hexagonal, or irregular crystals, and the frequency of mycelia branching gradually decreased with the extension of stress time.The electron micromorphology showed that some hypha was shriveled and shrunken after 48 hours stress.Wrinkled hypha increased after 72 hours stress.More and more crumpled hypha and flocculent impurities were produced after 96 hours of stress.The recovery ability of hypha was 24 hours＞48 hours＞72 hours＞96 hours.