The paper introduces characteristics of digital libraries as well as the connotation and structure of PKI technology,it points out that introducing PKI technology can solve the problems which have emerged in library digitalization process, such as copyright protection, information security and interlibrary cooperation. However, the development level of PKI technology in China is not high, adopting PKI in library is still facing obstacles including lack of technical staffs, key technology and cost, the application of promoting technology still needs more endeavors.