The amount of wood residue is used as a measurement of the extent of wood liquefaction. Characterization of the residue from wood liquefaction provides a new approach to understand some fundamental aspects of the liquefaction reaction. This paper adopts X-ray diffraction to characterize the changes of groups and mechanism of reaction of the residue crystallinity in the liquefaction process of Chinese Fir. The XRD analysis of liquefaction residue showed that amorphous region is firstly damaged so that the crystallinity could be in the trend of increasing in the liquefaction process of Chinese fir in most cases with the time’s prolonging. However, cellulose crystalline region begins to be destroyed under the higher liquefied temperature (170℃）or in the case of higher P/W (w/w) ratio (5), leading to the relative decreased trend of crystallinity. <br /><strong>Key words:</strong> Chinese Fir; XRD; Liquefaction; Residue