Life-long learning society is a society everyone must continue his learning activities in order to keep up with the process of the times. Adult education is the symbolic of life-long learning. Self-directed learning is one mean of adult education. How can library or public library contribute to self-directed learning is a very important thing in librarianship. In this article the relationship of library and self-directed learning, and four kinds of factors that affect the relationship and achievement of above are discussed.