The concept of "ntigen"is a relative one. The narrow concept of it condenses the process of activation of adaptive immune response and re-recognition of the same antigen, revealing the protective mechanism of vaccines with great significance for research and development of vaccines. However, the narrow concept involves adaptive immune system members: B cells, T cells and their effector products, which is difficult for beginners to understand the inherent meaning. Meanwhile, antigen classification fully summarizes the immune response process, so a variety of classification approach increases the difficulty in learning. Our teaching team analyzes the difficulties of this chapter in depth, and we implements the strategy that takes antibody structure and function as the breakthrough point and simplified adaptive immune response process as the core in teaching. A mind map that includes the main contents of this chapter is made during the process, which promotes the effectiveness of classroom teaching greatly.