Abstract: Study on hydrogen transfer and catalyst mechanism in complex multi-phase system is of significance for a better understanding of coal liquefaction process, hydrogen utilization and coal conversion from heavy component to light.Autoclave test was carried out under the atmosphere of N₂ and H₂ with Nao Mao lake coal and tetralin as raw material and a comparative study on catalyst and non-catalyst system was presented.Hydrogen transfer and catalyst mechanism in the complex multi-phase system of direct coal liquefaction were discussed under different atmospheres including thermal cracking in nitrogen, catalytic cracking in nitrogen, thermal cracking in hydrogen and catalytic cracking in hydrogen.The results show that catalyst promotes the activation of hydrogen and accelerates activated hydrogen to transfer to coal pyrolysis products and solvent.Catalyst promotes hydrogen in solvent transfer to coal pyrolysis products as well.Catalyst is beneficial to the improvement of the coal conversion and oil yield.Compared to hydrogen, solvent's contribution to activated hydrogen is twice as hydrogen in the condition of the experiment.Activated hydrogen from hydrogen and solvent is proportional to the conversion of coal and asphaltene to oil and gas.