[Objective] This study aimed to investigate the biological characteristics of parasitic Fusarium fungi from tibetan Cordyceps sinensis. [Method] A Fusarium strain was isolated from fresh tibetan Cordyceps sinensis as the experimental material, to observe the morphologies of Fusarium mycelium and spores. [Result] The isolated Fusarium fungus strain grew lushly on rice medium, with white and villiform myceliurn, and the villous stroma appeared in colors from beige to pink. After cultivated at (18 ± 4) ℃ for 14 d, the Fusarium strain produced milky white protrusions containing pale yellow chlamydospores, which can be divided into microconidiums and macroconidiums based on the different sizes. According to Ainsworth's classification system, the isolated strain belongs to Fusarium, Tuberculariales, Hyphomycetes, adelomycete subphylum. Further observation identified three types of macroconidium, and two of them showed distinct morphology, which was not described in Ainsworth's classification system. [Conclusion] The structure of the strain isolated from tibetan Cordyceps sinensis is significantly different from that of Fusariurn fungi recorded in relevant literatures, which requires further investigation.