Abstract: The composition of coal pyrolysis products can be regulated by hydrogen-rich atmosphere.Understanding regulatory mechanism of products can promote process optimization and industrialization.The coal pyrolysis experiments using Naomaohu coal as coal sample were performed in a fixed bed reactor in N2,H2 and CH4 atmospheres.In this paper,tar yield,the contents of each fraction and composition in tar from coal pyrolysis at different reaction temperatures and atmospheres were compared to understand the role of CH4 in coal pyrolysis at low-medium pyrolysis temperature (400~700 ℃).The results show that the tar yield of coal pyrolysis is enhanced in CH4 atmosphere above 600 ℃.The tar yield in CH4 atmosphere is slightly higher than that in N2 atmosphere at 600 ℃.The tar yield in CH4 atmosphere is significantly higher than that in N2 atmosphere at 650 ℃,and lower than that in H2 atmosphere.The simulated distillation results show that light oil and naphthalene oil are mainly produced below 450 ℃ during coal pyrolysis,the formation temperatures of wash oil and asphaltene are mainly concentrated below 600 ℃,and the formation temperatures of phenol oil and anthracene oil are concentrated below 500 ℃ and 550 ℃,respectively.The content of anthracene oil in tar is enhanced in CH4 atmosphere above 600 ℃.When the temperature is higher than 650 ℃,the CH4 is conducive to the formation of each fraction in tar,of which light oil and phenol oil are greatly increased.The content of light oil is higher than that in H2 atmosphere,and the content of phenol oil is basically the same as that in H2 atmosphere.The GC/MS results show that the formation temperatures of aliphatic hydrocarbons,olefins,ester and alcohol compounds are mainly concentrated below 450 ℃ during coal pyrolysis,and the formation temperatures of aromatics and phenolic compounds are concentrated below 600 ℃.The contents of phenolic and alcohol compounds in tar are enhanced in CH4 atmosphere above 600 ℃.The contents of aliphatic hydrocarbons,aromatics,olefins,ester,and alcohol compounds in tar are enhanced in CH4 atmosphere above 650 ℃.The content of phenolic compounds is greatly increased,which is slightly lower than that in H2 atmosphere.The CH4 can provide·H and·CHx for coal pyrolysis to participate the stability of coal pyrolysis free radicals and the secondary reaction of primary volatiles,when the temperature is higher than 600 ℃.