The complexes of dissolved organic matter(DOM)and polycyclic aromatic hydrocarbons(PAHs)play an important role in environmental behaviors of PAHs.Interactions between DOM and PAHs are involved in forming complexes of DOM and PAHs.However,besides partitioning and hydrophobic effects,little is known of the interact ions between DOM and PAHs. In the paper,the interactions of DOMs derived from paddy soil,pig manure and sewage sludge respectively with phenanthrene (Phe)and pyrene(Pyr)were investigated with Fourier transform infrared(FT-IR)spectroscopy.With all the DOMs tested,asorption peaks were found in the bands of 4 000~3 000 cm^-1,2 969~2 900 cm^-1,1 700~1 375 cm^-1,1 300~1 000 cm^-1,and 900~600 cm^-1,suggesting that DOM contained O-H(hydrogen bonded alcohols,phenols and carboxylic acids),NH(amines),aromatic ring,C-O(polysacchrides,carboxyl),and-CH₂ function groups.Comparison of the FT-IR spectra of DOM and DOM-Phe/Pyr revealed that absorption peaks of DOM-Phe/Pyr in the bands of 4 000~3 000 cm^-1,1 700~1 375 cm^-1,and 900~600 cm^-1 shifted to longer wavelengths,indicating that there existed NH-π and π-π interact ions in the formation of complexes of PAHs and DOM.