The ADSL(asymmetrical digital subscriber line) is a new technology which provides subscribers with broadband services by using the existing twisted pair lines in the telephone network. In this dissertation, the basic concept and features, system composition and technical performance of asymmetrical digital subscriber line(ASDL), as well as broadband services provided by ADSL etc, are described and explained. Mainly introduces the principle of ADSL technology and the main idea , function, features and application based on ADSL technology on campus network. It may be pointed out that, using ADSL, residential broadband information could be transmittd over ordinary twisted pair line in the transition period which may be several decades to fiber-to-the-home.