Abstract: The influence of initial hydrogen pressure on hydroconversion of C7-insoluble asphaltene in THAR (Tahe atmospheric residue) was studied by autoclave with decalin as a solvent. The results show that the yield of gas plus gasoline increases, the coke yield decreases when the initial hydrogen pressure increases from 8.0 MPa to 14.0 MPa. The maximum asphaltene conversion and diesel yield and the minimum hydrotreated residue are obtained at 12.0 MPa. The increase of initial hydrogen pressure is beneficial to the conversion of asphaltene, but the exorbitant initial hydrogen pressure has adverse effect to the conversion because the oil-film on catalyst become thicker and is harmful to the diffusion of reactant into catalyst. With the increase of initial hydrogen pressure, the desulfurization rate, denitrification rate, and the molecule weight of hydrotreated asphaltene are decreased, but the change decreases with the increase of hydrogen pressure.