The secondary metabolites of actinomycete H4-5 fermented mycelium collected from the sediments of offshore mangroves were studied.A variety of chromatographic techniques were used to separate and purify compounds from the 95% ethanol extract of actinomycete H4-5 fermentation mycelium.By spectroscopic methods combined with literature data comparison,13 compounds were isolated and identified as cyclo-(L-Pro-L-Asn) (1),uracil (2),uridine (3),2′-deoxyuridine (4),thymidine (5),β-adenosine (6),2′-deoxyadenosine (7),stigmasta-7,22-diene-3β,5α,6α-triol (8),ergosterol (9),N-(2-Phenethyl)acetamide (10),methyl 8-(3-octyloxiran-2-yl)octanoate (11),tetrahydro-5-oxo-2-furancaboxylic acid ethyl ester (12),cyclo-(L-Leu-L-Val) (13).The cytotoxicity of these compounds to three human cancer cell lines was tested by MTT method,and their anti-inflammatory activity was tested by LPS-induced macrophage NO release test.The results showed that these 13 compounds had no obvious effect on the tested cancer cell lines, but compound 2 shows certain anti-inflammatory activity.