Abstract: Based on the traditional composition design concept, a new design concept of “near-mixing enthalpy + effective atomic size difference” component imbalance diffusion was proposed in this paper, and it was first used to design the titanium-based amorphous alloy powders. Titanium-based amorphous alloy powders, Ti₆₀Mn_20‒xCu_20+x (x=0, 10), were successfully prepared by mechanical alloying method, and the amorphous forming ability, thermal stability, and microstructure of this alloy system were conducted. The results indicate that the new design concept of “near-mixing enthalpy + effective atomic size difference” component imbalance diffusion can realize the optimized design of the component compositions for the Ti‒Mn‒Cu alloy system. The Ti₆₀Mn_20‒xCu_20+x (x=0, 10) alloy powders exhibit good amorphous forming ability and high thermal stability. Compared to Ti₆₀Mn₂₀Cu₂₀, Ti₆₀Mn₁₀Cu₃₀ forms the amorphous alloy powders more easily, which is consistent with the results predicted by the theoretical model of amorphous forming ability.