Abstract: The antifungal activity of the fermented extract of a dominant endophytic Umbelopsis dimorpha VDG10 from the roots of Vaccinium dunalianum against plant pathogenic fungi was evaluated using the disk diffusion method, and its chemical composition was analyzed by UPLC-QTOF-MS/MS. The results demonstrated that the fermented extract exhibited broad-spectrum antifungal activity on 7 phytopathogenic fungi. A total of 3164 compounds were identified, including 840 alkaloids, 477 shikimate-phenylpropanoids, 453 amino acids/peptides, 410 terpenoids, 347 fatty acids, 173 carbohydrates, 148 polyketides, and 316 other compounds, with relative contents of 21.296%, 16.796%, 19.968%, 9.677%, 18.394%, 8.107%, 1.107%, and 4.657%, respectively. Among these, 40 compounds with a relative content greater than 0.5% were considered the major metabolites in U. dimorpha VDG10.