【Objective】 To study the metabolites of a mangrove fungus Fusarium sp. R5. 【Method】The fermented filtrate of R5 fungus was isolated by silica gel column chromatography. The structures of the metabolites were characterized by spectral analyses. The antifungal activities were investigated using the paper disc-agar diffusion method. 【Result】Ten compounds were isolated and identified as 5-hydroxymethyl-2-furaldehyde (compound 1), (3R,4R)-cis-4-hydroxymellein (compound 2), (3R,4R)-cis-4,7dihydroxymellein (compound 3), clavatol (compound 4), flazine (compound 5), ergosta-4, 6, 8(14), 22-tetraen-3-one (compound 6), β-sitosterol (compound 7), 3β-cholest-5-en-3-ol (compound 8), butanedioic acid and maleic acid. At the concentration of 250 μg·mL^-1, compound 5 showed high inhibitory activity against Colletotrichum musae (Berk.&M. A. Curtis) Arx.， compounds 5 and 6 showed moderate inhibitory activity against F. oxysporum and F. graminearum Schw.【Conclusion】Compounds 1～8 are isolated from Fusarium sp. and among them, compounds 5 and 6 could be used as the lead compounds in antifungal agents.