Abstract: This paper makes a research on the core value of the digital library, discriminates social roles between the busi- ness digital library and the public-interest digital library by copyright balance theory, oints out that the public- interest digital library is the extension of the traditional library and follows the irreplaceable social values of the traditional library, fulfills the core value which is conferred by right.

Key words: digital library; core value; library right; intellectual property rights