This paper firstly proposes a digital resource system of university libraries oriented to knowledge service for digital library resource evaluation research, which mainly consists of a knowledge service diamond system and digital resource diamond system, and studies the evaluation elements and evaluation process of this system, then constructs the evaluation system of library digital resources from quantitative evaluation and qualitative evaluation, etc., and through multi-level topologizable theory, the evaluation indexes and The evaluation indexes and the correlation function are calculated by multi-level topology theory, to derive the weight coefficients and comprehensive superiority of the evaluation indexes, and an example analysis of the digital library based on multi-level topology optimization decision making is conducted. The results show that the users’ comprehensive evaluation of digital library decision-making is excellent, S2, S5 is good, S3 is medium, and S4 is average, where S5 has a higher comprehensive correlation degree in the good level than the correlation degree of S2, indicating that this study improves the quality of digital library decision making in universities and then better serves the users.