The direct liquefaction products of Paulownia paulownia using iron powder as catalyst in deionized water at 280~360°C were analyzed by Fourier transform infrared spectroscopy, and the effects of reaction temperature on the direct liquefaction process and heavy oil and light oil components of Paulownia biomass were investigated by comparing the infrared group differences between raw materials and residues. The results showed that with iron powder as catalyst, the reaction temperature had a significant effect on the liquefaction process, and the hemicellulose and cellulose in Paulownia were completely reacted at 320°C. Lignin degrades from 280°C, and the solid residue also contains an aromatic ring structure in the reaction temperature range. The functional group of the final liquefied product heavy oil is not greatly affected by the reaction temperature; Heavy and light oils are complex mixtures that contain various compounds such as hydrocarbons, aldehydes, ketones, carboxylic acids, phenols, and esters.