looking at the development of subject librarians and subject services in chinese libraries during the past decade, this paper highlights the innovative concepts and practices of subject librarians in national science library (nsl), chinese academy of sciences (cas). after a two-year trial period, nsl, cas, with 39 full-time subject librarians, has begun to provide personalized, subject-speci.c, and knowledge-based services to the end-users since 2006. such a practice manifests that subject librarians and subject services should be embedded into the research process and working environment. and, the subject service should be made available to the users beyond the space restriction and time limit, and .nally create a congenial environment for users. librarians should develop new expertise to offer the user-oriented service, changing the role from book keepers to research instructors, advisors, even chief information officer (cio) or chief knowledge officer (cko).