The liquefaction processes of lignin with and without heteropolyacid salt catalysis at 260-320 degrees C for 45 min were investigated; the effect of different liquefaction solvents (such as iso-propanol, ethanediol, and propylene glycol) on the chemical compositions of bio-oil was also studied. It is found that the maximum lignin conversion of 73.4% can be obtained when the catalyst content was 0.02 g in the presence of iso-propanol at 300 degrees C. The experimental results showed that the presence of heteropolyacid salt can improve the conversion of lignin; different chemical compositions were observed in bio-oil obtained from iso-propanol, ethanediol, and propylene glycol liquefaction because of the different hydrogen-donor capacity and reactions with intermediates. The residues were analyzed by Fourier transform infrared spectroscopy, scanning electron microscope, thermogravimetric analysis-differential thermoanalysis, and elemental analysis. The results demonstrated that the residues still maintain the microstructure of the lignin.