This study aims to investigate the chemical constituents from the rice fermentation of Xylaria longipes and their biological activities.Three polyketones were isolated from the ethyl acetate layer of the rice fermentation of X. longipes by silica gels,Sephadex LH-20 column chromatography,and HPLC methods.Their structures were established based on NMR,MS and other spectroscopic techniques.1-(3-Ethyl-1,2,6-trihydroxycyclohexyl)-3-hydroxy-2-(methoxymethyl)propan-1-one (1) is a new compound. (2E,4E)-6,8-Dimethyldeca-2,4-dienoic acid (2) and (2E,4E)-8-methyldeca-2,4-dienoic acid (3) were reported as natural products for the first time.Their antiproliferative activities of compounds against three cell (keratinocyte HaCaT cell line,concanavalin A-induced T cells,and lipopolysaccharide-induced B cells) were evaluated,but none showed significant activities.