Abstract: As a paradigm of multiple rationality, instrumental rationality means to achieve the maximization of efficiency or utility through rigorous logical thinking and precise scientific calculations. Liberal political romanticism strives to ensure the realization of citizens’ individual democracy and freedom rights through the transplantation, design, construction and perfection of the system. Andthe institutional rationality in instrumental rationality plays an important role in the process of the formation of liberal political romanticism. Specifically, theargument basis of instrumental rationality leads the value direction of liberal political romanticism, the institutional concern of instrumental rationality establishes the hopes and the preferences of liberal political romanticism, and the thinking characteristics of instrumental rationality shape the cognitive logic of liberal political romanticism, moreover,the core proposition of instrumental rationality promotes the behavioral model of liberal political romanticism.