Abstract: The TiB2-Co-Cr-W composite powder was prepared by mechanical alloying using a high-energy ball milling process. The effects of ball milling time, ball material ratio and ball milling speed on the particle size of the composite powder were investigated by means of orthogonal tests. The effects of ball milling time, ball material ratio and ball milling speed on the refinement process and alloying process were investigated by XRD, SEM and TEM, respectively, TiB2-Co-Cr-W cermet composites were prepared by pressureless sintering. The results show that the ball milling time has the most significant effect on the refinement of the powder particles, while the ball material ratio has less influence on it. The optimum ball milling process was: ball-to-material ratio of 10:1, ball milling speed of 150 r/min and ball milling time of 48 h. The TiB2-Co-Cr-W composite powder prepared under the optimum ball milling process showed obvious alloying effects, with the TiB2 diffraction peak broadening, peak intensity decreasing and lattice constant decreasing, and some metal elements solidly dissolving into the TiB2 crystal structure, forming solid solution and amorphous material. Finally, the relative density of TiB2-Co-Cr-W composites obtained by pressureless sintering at 1600℃ for 1 h reached 98.8%, and the opening of the porosity is 0.1%.