Abstract: Molybdenum and graphite were welded in vacuum at 1 650 ℃ for 1 h using Cr-Ni powders Cr-Ni-Cu thin sections, and Ti-Ni-Zr powders as the interlayer respectively by transient liquid phase diffusion bonding technology. The welding joints were sheared to analyze the microstructure and composition. The results show that molybdenum and graphite could be welded together and certain strength could be acquired with the three different interlayers. The greatest shear strength was got when the Ti-Ni-Zr powders were used as the interlayer, which was stronger than that of graphite. There was brittle microstructure in the welding joints interface, whose distribution was effected by composition of the interlayer and the solid solution. And there were a large number of micro-cracks existed in brittle microstructure, which was one of the factors affecting the shear strength.