Hardwood　residue　(HR),　a　byproduct　of　paper　industry,　was　liquefied　by　using　polyethylene　glycol　400　(PEG400)　and　ethylene　carbonate　(EC)　as　the　liquefaction　solvents,　and　concentrated　sulfuric　acid　as　the　catalyst　to　produce　bio-polyols　(HRLP),　which　were　used　to　synthesize　polyurethane　(PU)　foams.　The　effects　of　conditions　on　the　properties　of　HRLP　and　modified　PU　foams　were　investigated　and　the　mechanism　of　biomass　liquefaction　was　discussed.　The　optimum　conditions　of　liquefaction　were　obtained　as　follows:　reaction　temperature　of　160　°C,　reaction　time　of　60　min,　ratio　of　PEG400/EC　of　8:2　(w/w),　and　ratio　of　liquid/solid　of　5:1　(w/w).　The　characterization　of　HRLP　modified　PU　foams　suggested　that　HRLP　could　partially　replace　the　petroleum　polyols　to　synthesize　PU　foams.　With　the　increase　of　the　replacement　percentage　of　HRLP,　the　apparent　density　and　compressive　strength　of　the　foams　increased　firstly,　and　then　decreased.　Meanwhile,　the　thermal　stability　was　improved　slightly.　©　2016,　Wuhan　University　of　Technology　and　Springer-Verlag　Berlin　Heidelberg.