The Cu-Ti bimetallic composites were prepared by liquid-solid composite process, and the diffusion behavior of Cu and Ti elements at the composite interface was investigated by OM, SEM, EPMA and other testing methods. The results show that the grain boundaries are the main channels for diffusion in the process of Cu/Ti composite. Except for part of the Cu₄Ti phase formed on the Cu matrix, the rest of the compound phases of the diffusively-dissolved layer are generated on the Ti matrix. The compounds generated at the Cu-Ti composite interface are Cu₄Ti, Cu₃Ti₂, CuTi and CuTi₂, where the Cu₃Ti₂ phase grows in a “jagged” manner, the CuTi phase grows in a “bamboo shoot” manner, and the CuTi₂ phase grows in a “planar” manner. The hardness values of the diffusion-dissolved layer are significantly higher than those of the two pure components. As verified by the Miedema model, the sequence of interfacial phase precipitation is CuTi, Cu₃Ti₂, CuTi₂ and Cu₄Ti. The bonding of Cu and Ti is a combined action of Cu diffusion in Ti matrix and Ti dissolution in the Cu solution.