Abstract: By means of FTIR and GPC, the liquefaction of cellulose from walnut shell under acid catalysis condition in the presence of phenol was discussed by taking the residue content, contents of free phenol and brominable substance as indices. The results showed that the liquefaction process of cellulose from walnut shell in the presence of phenol under acid condition was essentially a slow degradation process of cellulose. When the cellulose was degraded to low molecular fragments such as oligosaccharides, there was possibly the breakage reaction of pyranoid ring simultaneously. When the semi-product from cellulose liquefaction reacted with phenol, the liquefied product, which could be dissolved in phenol, was formed and the content of free phenol and brominable substance decreased along with the reduction of residue and molecular weight during liquefaction.