Facing the needs of new liberal arts construction, university libraries need to actively carry out service innovations to respond to the call for new liberal arts construction, and undertake the new mission of university libraries in the era of digital intelligence. The article sorts out the development and evolution process from subject services to subject data services, and constructs a "big data + small data" subject data service model based on the data life cycle theory, and then proposes corresponding implementation strategies. The article believes that university libraries in the era of digital intelligence should establish the concept of big data thinking, reshape the library subject service model according to the needs of new liberal arts construction, provide efficient, accurate, and professional subject data services, and comprehensively improve the service level and quality of subject data services.