With the advent of the civilian spreading era, research in diffusion of word-of-mouth reemerged. In particular, diffusion of electronic word-of-mouth under the Internet environment caused a big concern of practitioners as well as scholars. We summarize and comment on the classical research of diffusion of word-of-mouth and electronic word-of-mouth literature at home and abroad from the perspectives of intensions, theories, subjects, objects, effects, processes and research methods. Based on this, we establish a comprehensive theoretical framework to explain diffusion patterns of electronic word-of-mouth.