Blog, as a new network interactive mode and the tool of information generation, storage, spreading and knowledge management, has become an increasing concern of educators and applied to the modern distance education. This paper discusses the concept,the features of the Blog and the research of application of Blog to modern distance education in five aspects covering individualized knowledge management, building a resource-sharing platform, realizing collaborative learning, supporting multiple evaluation, and educational narrative research., thus reveals the positive roles and significance of Blog in modern distance education.