Abstract: Product R&D process is quite complex; it is regarded as a “black box” by economist and innovation scientist. The microcosmic process of product R&D is attempted to clean up at the perspective of the mechanism of technological evolution by studying literature. The underlying factors of product R&D process as well as how they mutually affect and induce new techniques are illustrated; the idiographic forms, conditions, and characteristics of technological evolution in product R&D are clarified; and the effective implementation of trial-and-error, technological reverse, technic disassemble and integration as well as the development skills of technology inosculation, inoculatiion, and variation are described.