To solve the problem that it is difficult to calculate system coupling in the field of systems science and software engineering, this article discussed quantitative analysis of system coupling. It is difficult to calculate system coupling in the field of system science and software engineering. Consequently, this paper discussed quantitative analysis of system coupling to solve this problem. According to the dependencies between the entities in a system, this paper proposed two mathematical models to measure system coupling based on entropy and judgment matrix. With these two models, it is possible to measure the coupling of each entity in the system and provide a basis for reducing the system coupling. Finally, this paper verified the validity and utility of the proposed models via a case of data warehouse structure.