Abstract: With the rapid growth of digital resource, and the increasing demands on individual and deep knowledge discovery service, as well as the unprecedented prosperity of machine learning, the librarians see a bright future for using machine learning technology to improve library discover. This paper introduced machine learning technology and current situation of library discover briefly, analyzed the necessity of applying machine learning technology in library discover, and finally took Yewno, a discovery tool based on knowledge graph, as the example, to reveal a visual knowledge network with the conception and relation as the core and the exploration of deep connection of knowledge.