[Purpose/significance] Establish a kind of effective and operable method which can evaluate quantitatively needed extent and academic level of a journal as well as guarantee ratio and quality of library for the journal, with which clarifying importance of a journal for a subject and guarantee level of the journal in library, to provide complete and exact information for plan and construction of journal resource of library.[Method/process] With a case of philosophy major in Jilin University and introduction of concepts of used ratio of journal and guarantee quality, the need degree and academic level of journals are described quantitatively by using arrangements of the used ratio and citied frequency of journals selected by the faculties working in the major to publish their papers or cited in their literatures from high to low, and statistical laws of the arrangements. The guaranteed level of the journals in library is proposed to be evaluated by considering whether the journals are core journals given by Peking University or SCI (SSCI or A&HCI)journals and their positions in the cited frequency and used ratio arrangements. [Result/conclusion] It is found that change of both cited frequency and the used ratio with order number of journal follow decay exponential law. Compared to traditional cited frequency and guarantee ratio methods, the used ratio arrangement can describe the need degree of a journal by a subject more accurately, and the guarantee quality can reflect guaranteed level of the journals in library.