In recent years, joint teaching has emerged as a significant teaching modality in the undergraduate design courses of the architecture department. By crawling and collating the information of joint teaching for undergraduate students majoring in architecture of various types nationwide in the recent five years, it was discovered that joint teaching courses for the third-year students were scarce. However, the third year plays a connecting role in the five-year teaching system, and joint teaching holds multiple positive significances for the design courses of the third year. The joint teaching program for the third-year students of architecture, which was initiated and participated in by the Department of Architecture of Suzhou University of Science and Technology, has been held continuously for six sessions to date. It has accumulated a set of feasible and effective practical approaches in course design and refined some innovative teaching characteristics. In the teaching research, students' evaluations on various aspects of the joint teaching in the third grade were investigated through long-term tracking surveys using online questionnaires. From this, the experience and achievements of the joint teaching in the third grade were summarized, and improvement suggestions were provided for future joint teaching.