The public architecture design course of architecture major in Hefei University of Technology carried out the short period teaching reform under the guidance of constructivism, which changed the traditional teaching idea and improved the teaching effect. By reviewing the new needs of the society and the new characteristics of students, this paper analyzes the current situation of shortening the class hours of public architectural design course and the origin of the short cycle teaching reform of public architectural design course, puts forward the teaching objectives of cultivating logical ability, innovation ability, comprehensive ability and self-learning ability, and explores the constructivism teaching mode and teaching organization matching with architectural design course. This paper introduces the short cycle teaching practice of public architecture design course for sophomores majoring of architecture specialty of Hefei University of Technology in 2020 from five aspects: task interpretation, teaching methods, topic research, concept generation and design improvement. It also reflects on the short cycle teaching under constructivism, and finds that it is still necessary to further strengthen the awareness of participation, self-determination, demand different consciousness and subject consciousness.