Over the past decade, learning engagement has received increasing attention from researchers. As a critical factor in college students’ academic achievement, learning engagement is significant in students’ long-term future development and social creativity. Present studies show that the overall level of college students’ learning engagement is low, which is highly unfavourable to educational quality and long-term development. There is no doubt about the position of the university library in academic circles. However, the influence of the university library environment on college students’ learning engagement has not been fully explored. The data in this study came from a survey of 45 Chinese universities. This paper investigates the relationship between the university library environment, students’ interaction, and students’ learning engagement. The results showed differences in Chinese college students’ learning engagement in liberal arts and sciences majors. The learning engagement of liberal arts majors is much lower than that of science students. We found that the library environment has an important influence on college students’ learning engagement. And the library environment can affect college students’ learning engagement through the intermediary role of interactive participation among students. In addition, for liberal arts students, the direct effect of the library environment on their learning engagement is more significant. However, for science students, the influence of the library environment on their learning engagement is more strongly intermediated by the students’ interaction. Therefore, future construction and renovation of library environments should cater not only to the diverse needs of different academic disciplines, especially liberal arts students who need special attention but also guide more students to interact friendly through the spatial characteristics of the library so as to improve the overall learning engagement of college students.