Nowadays, Internet has become the motive power to accelerate changes of our life. The copy distribution of a large number of works is become easier more than ever before through the network. However, with the development of computer and internet technology day by day, kinds of disputes of copy and transformation in direct or indirect through various digital products and services are happening with increasing frequency.The question on protection of digital copyright also has aroused increasing attention around the world recent years. Especially in China, through a report of CNNIC(China Internet Network Information Center), total number of netizens of China has now reached the first place in the world in place of USA by the end of June, 2008. And according to the China's "Top Ten Brand Events Ranking List" in 2009, half of all China's brand events were related to network disputes. But at the same time, awareness and management on the importance of protection of digital copyright in China is still deficient.The core of traditional copyright industry is transfer of copyright, authors creative works, and then authorize copyright to publications, and eventually spread to users. Although under new technology condition, process of digital copyright industry is more complex, the core is still to balance the benefits among author, publication, user and so on. Recognizing these points, this thesis aims to discuss why we need to protect digital copyright. Another purpose is to explore comparatively the main legal regulations about digital copyright protection. Besides, more important aims is to obtain some implications from analysis of digital copyright disputes among the major countries and Long Tail Theory.To attain these aims, with the literature analysis and case analysis methods, this thesis is composed as follows: Chapter 1 explain background, aims, scope, and methods of the research. Chapter 2 study on definitions, characteristics and the necessities on protection of digital copyright. Chapter 3 review the international regulations about digital copyright in model world. Chapter 4 explain the current situations of China, U.S., and Korea on protection of digital copyright. Chapter 5 analyze the recent disputes in connection with the digital copyright of Digital Library, P2P Program, Music Files in China, USA and Korea and explains some implications obtained from these cases and Long Tail Theory. Final Chapter 6 summarize and discuss main implications of the previous research.As a result of this study, following are that is considered as important.First, there are not so many legal suits in relation to digital copyright law. However, WTO/TRIPs and some regulations from WIPO pursuit proper exercise when copyright-holder take an action for legal remedy, seeking for balancing between his right and public benefit.Second, a good copyright law is to regulate the benefits among all parties during the process from authors to end-users perfectly. we need to protect author's rights to encourage literary and artistic creation and also need to limit author's rights to ensure public interests. So basic requirement for digital copyright mechanism is to improve the operational efficiency of copyright and then ensure the spread of literary and artistic works widely.Third, internet has changed people's economic idea a lot, through the Long Tail Theory, the sum of many small markets is equal to or more than the some big markets, "Long Tail" markets such as online media, digital distribution, online games, comic & animation will bring more business opportunities in digital copyright industry.