Abstract: Multilayers diamond-like carbon film, which was composed of several thick diamond-like carbon layers and thin germanium island layers, was prepared on the germanium substrate in order to resolve the high inner-stress in the diamond-like carbon film. The diamond-like carbon layers had the main function of protection, and the germanium island layers had the buffer function to reduce the inner-stress in the diamond-like carbon film. Meanwhile, the thicknesses of the germanium layers were very thin, so they had no influence on the mechanical and infrared performances of the whole film nearly. Inner-stress in the multilayers diamond-like carbon film was 2.14 GPa, 39% lower than that of the pure diamond-like carbon film, and the multilayers diamond-like carbon film could pass the friction test stipulated in the GJB2485-95'general specification for optical coatings. The hardness of the multilayers diamond-like carbon kept high hardness of 47 GPa, and had the same surface roughness to the pure diamond-like carbon film. Therefore, the multilayers diamond-like carbon film could be used as practical protective film for infrared window.