In order to enable students to fully understand the importance of design patterns, identify design patterns in demand analysis, and apply them flexibly, a teaching case integrating builder, abstract factory, strategy and facade design patterns is designed through two explicit iterations and three invisible iterations. Firstly, the design concept of the case is elaborated. Then the iterative process of the case teaching is described in detail. Finally, practical teaching tasks are decomposed based on the case, and the effectiveness of case teaching is evaluated. The practical results indicate that this case can stimulate students' interest in learning design patterns and improve their ability to use design patterns for object-oriented problem solving.