Abstract: In order to study the ablation properties of C/C composites influenced by copper infiltration, C/C-Cu composites were prepared by chemical vapor infiltration (CVI) and liquid pressure infiltration processes.The ablation properties of C/C-Cu composites were verified using a plasma ablation device.The results show that the preparation period is significantly shortened with the addition of Cu in C/C composites.Cu uniformly distributes in C/C composites and forms a continuous network structure.The linear ablation rate of C/C-Cu composites is lower than that of C/C composites in the initial stage within 30 s of ablation, because the melting of Cu could absorb a lot of energy and reduce the heating rate.With the ablation time increases, Cu on surface of C/C-Cu composites is blowing away by plasma flames, the sample surface of C/C-Cu composites becomes a lower density porous C/C framework.Therefore, the linear ablation rate of C/C-Cu composites increases violently, and becomes higher than C/C composites', the ablation resistance of C/C-Cu composites decreases evidently.