Diamond, as one of the most special materials in natural world, is featured with the highest hardness, low friction coefficient, high elasticity modulus, high thermal conductivity, high insulation class, wide energy gap, great sound propagation rate and favorable chemical stability, which are presented in Table 1. In spite of such unique features, the natural diamond has always been existed in the form of gem, with its variability and rareness sharply limiting its application. Diamond film, on the other hand, integrates such physical and chemical properties, with lower cost than natural diamond and applicable to be made into various shapes, thus enjoying extensive application prospect in electronic industry, optical field and mechanical industry.