This paper intends to describe the concepts and historical development of electronic library, to examine some of information technologies such as CD-ROM, electronic books, multimedia and networks, and to analyze cases of electronic library. Electronic library is able to offer many services in digital form, ranging from bibliographic databases on CD-ROM running on standalone computers, to fully networked abstracts and texts, available inside and outside the library. For users, the electronic library is a means of improving the speed of access to library materials, of providing a simple means of the selecting materials amid the glut of information available, and of eliminating the need to visit a library for many information inquires. In summary, electronic library has the potential to give scholars better service than conventional libraries, at a lower cost. However, remember that, today, almost all these benefits are still potential.