A new cooling structure of C/C composites was made to use in high temperature environment over 2000 K. A stainless steel tube was used as a cooling channel. The stainless steel tube was fixed to the C/C composites by the elastic force of each material. The performance of the cooling structure was evaluated by heating tests and numerical analysis. In the result of the numerical analysis, it was shown that the surface can be cooled below 2000 K under the condition of surface heat flux of 10 MW/m 2. However, it was shown experimentally that the cooling performance gets extremely worse due to the plastic deformation of the tube when the temperature of the tube rises more than 600 K.