In the conventional five-year undergraduate architectural design teaching system, the second-year design teaching can be regarded as an introductory course for formally entering the training of architectural design methods, and the curriculum design goals at this stage are reflected in two levels, to guide students to understand the basic design logic and to master the rational design methods. Based on analyzing the problems of teaching methods that affect the training effect, such as the lack of teachability and orientation in conventional introductory courses, the second-grade teaching team of the School of Architecture in South China University of Technology proposes a decomposition introductory teaching concept for the above problems, and summarizes two aspects of design training innovation model as thematic teaching content decomposition and advanced guidance process decomposition. Taking the behavior and space topic of the course as an example, it summarizes the specific operation method of the decomposition teaching mode.