The　variations　in　the　structural　components　of　dissolved　organic　matter　(DOM)　during　coal　liquefaction　wastewater　(CLW)　treatment　are　still　unclear　at　present,　limiting　the　further　improvement　and　application　of　CLW　treatment　processes.　In　this　study,　the　changes　of　DOM　composition　during　air　flotation,　catalytic　oxidation,　biofiltration,　ozonation,　anoxic/oxic　(A/O),　and　membrane　bioreactor　(MBR)　which　were　applied　in　the　full-scale　CLW　treatment,　were　investigated　by　three-dimensional　excitation-emission　matrix　fluorescence　and　ultraviolet-visible　spectroscopy.　The　dissolved　organic　carbon　and　chemical　oxygen　demand　of　the　raw　CLW　reached　1965.2　mg/L　and　5310.0　mg/L,　respectively,　with　humic　acid-like　substances　being　as　the　dominant　component　(63.1%),　and　protein-like　substances　contributing　a　small　amount　(5.3%).　Air　flotation　could　treat　humic　acid-like　substances　more　effectively.　Catalytic　oxidation　and　ozonation　efficiently　removed　macromolecular　aromatic　substances　with　aliphatic　chain　substituents,　resulting　in　the　notable　enhancement　of　the　biodegradability　of　the　organics.　The　DOM　removal　efficiency　of　biofiltration　and　A/O　reached　86.0%　and　92.3%,　respectively,　and　simultaneously　complex　macromolecular　substances　with　a　high　degree　of　aromaticity　were　formed.　This　study　could　provide　a　theoretical　basis　for　optimizing　the　technical　parameters　and　further　improving　the　treatment　efficiency　of　CLW.　(C)　2019　Elsevier　B.V.　All　rights　reserved.