A systematic research about the liquefaction of alkali lignin in supercritical ethanol using ZSM-5 zeolite catalysts is reported, which includes the synergistic effect of temperature, catalytic content, and reaction time on product yield and distribution. Fourier transform infrared and gas chromatography-mass spectrometry analysis were carried out to evaluate the compositions of bio-oil and solid residue. Under moderate condition, maximum conversion and yield of bio-oil were satisfactorily high. With the help of ZSM-5 catalyst, lignin could be successfully converted into aromatic compounds.