Abstract: Samples from the fermentation beds in pig barns were extracted with petroleum ether,chloroform,ethyl acetate,acetone and ethanol.The quantities extracted by the various solvents were in the order of ethanol>acetone>ethyl acetate>chloroform>petroleum ether.Compositions of these extracts were determined using GC-MS.Esters and hydrocarbons were the main substances in the bedding materials.Petroleum ether and chloroform could more effectively extract the low polar esters and long-chain alkanes,and chloroform produced more compounds and unsaturated hydrocarbons than the others.The ethyl acetate extracts showed more olefin compounds(including polycyclic aromatic hydrocarbons)than those obtained by other 4solvents.Since acetone could effectively extract both alkanes and esters in a wide range of polarity,it was considered the selected solvent for the substance extraction.On the other hand,ethanol could be used to specifically extract high polarity esters.