The catalyst NiO/MgO-Al2O3 was prepared by loading magnesium and nickel onto the surface of gamma-Al2O3 beads, respectively, and was adapted to in situ upgrade the high temperature pyrolysis vapor derived from coal pyrolysis. The catalyst synthesis process, and structural variation were characterized by the XRD, SEM, and physical adsorption analyzer. In order to examine the catalytic effect on the different nickel loading ratio in the catalysts, the solid-liquid-gas product distribution, variation of gas and components of coal tar were studied by simulated distillation, GC/MS, elemental analysis and so on. The results shows both the tar yield and the content of the light fraction in the tar can be increased by catalytic up grade. The catalyst has a strong ability to convert the heavy component and polycyclic aromatic hydrocarbons in the tar to lower molecular weight components. (C) 2016 Elsevier Ltd. All rights reserved.