Libraries have been playing an important role in digital humanities,and their engagement in digital humanities deserves close attention. This paper makes an analysis of the dh+lib documents on the ALA website as well as other documents,and find out that libraries have been contributing to digital humanities mainly by means of resource construction,collaborative research,and teaching assistance. To promote digital humanities,libraries should improve their infrastructure and provide better service,organize qualified professional teams,and promote the dissemination of academic achievements.