Abstract: The volatiles’ reaction has a significant influence on composition and coking behavior of tar during low-medium temperature pyrolysis of coal, which is closely related to the activity of volatiles and the content of components rich in hydrogen in the system. By introducing tetralin, the effect of reaction of volatiles generated by pyrolysis of Naomaohu coal on the product distribution and coke yield was explored at various temperatures using a two-stage fixed bed reactor. The tar composition was analyzed by a comprehensive two-dimensional gas chromatography/mass spectrometry. The results show that the yield of coke is higher at 400 ^oC due to the weaker reaction between volatiles and THN and tar condensation. As the temperature increases, the reaction between volatiles and THN intensifies, resulting in the decrease of liquid products yield and the increase of gas yield. According to the calculated and experimental values of the reaction products of volatiles and THN, it is found that the liquid products yield increases after the introduction of THN. The contents of aromatic hydrocarbons with 2−5 rings and coke both decrease. This indicates that the interaction between volatiles and THN promotes the α−H transfer of THN and provides more active hydrogen for the reaction system. Besides, the interaction between volatiles and THN is also beneficial to the formation of phenolic compounds and other oxygenated compounds, especially for polyphenols. The activity of volatiles during coal pyrolysis is related to oxygen-containing radicals, which have a strong bond with active hydrogen.