Abstract: It makes information services really achieve discipline requirements researching the constituent elements of subject librarians＇ competency, ensuring subject librarians promoting continuously their competency under thenew competition environment through various effective measures. Based on the situaticn of the fusion of lots of subjects, this paper reveals the main elements of competency that subject librarians need, which in a methodeven enriches the research of subject librarians＇ competency elements, has certain reference value to the selecting and assessing of subject librarians.

Key words: subject librarian; competency; elements of competency; library; subject service