Mo–Si–Cr coating-modified C/C composites were prepared by pack cementation in argon. The high-temperature erosion resistance of Mo–Si–Cr coating-modified C/C composites was investigated in a wind tunnel. Bending moment distribution of the tested specimens in a wind tunnel was calculated and thermogravimetric analysis of the composites was measured. These results show that the Mo–Si–Cr coating-modified C/C composites could resist from high-temperature erosion in a wind tunnel at 1873K for more than 92h. Due to the high viscosity of SiO2, the Mo–Si–Cr coating-modified C/C composites lacked effective oxidation resistance from 700 to 1300K, resulting in extensive mechanical damage and the fracture of the tested specimens.