Acidic compounds in pyrolysis oil from an industrial unit were extracted and enriched, and then were analyzed by Fourier transform infrared spectroscopy, hydrogen nuclear magnetic resonance, elemental analysis, and gas chromatography/mass spectrometry, respectively. The results showed that the acid compounds were enriched in ethyl acetate isolates and acetone isolates. Content of O element in acid-rich components significantly increased. The acid-rich components consisted of much methylene and -C=C- structures. Further, 51.24% of the methyl ester products were identified, including carboxylic acid methyl ester (36.22%), chain hydrocarbons (13.41%), cycloalkanes (<1%), and alcohols (<1%).