Constrained by the budget, the library can't market itself by using the mass media. Therefore the Blog-an emerging Internet media-provides with a brand new opportunity toward the library marketing service. This article illustrates the content and the developing tendency of Blog, and introduces five reprehensive Blogs to the readers as references of library information service, demonstrating on how Blog markets the library service as a marketing device, and take ”Blogger.com” as an example to further explains the operation of Blogs.