During the teaching of geometric construction analysis in structural mechanics course, it was found that students did not master several key concepts, which may cause mistakes in problem solving. In order to improve the understanding of new concepts, the conceptual variation originating from pedagogy of variation was adopted in class teaching activities, which is based on the theory of knowledge visualization and cognitive load. According to some mistakes in students’ homework, the graphical representations of essential variation and unessential variation of the concepts, such as virtual hinge, hinged triangle and binary system, were provided to complement the original explanation of the new concepts. Owing to the conceptual variation teaching method, the students’ cognitive load in learning was reduced and the long-term memory was formed more easily. Finally, the teaching effectiveness was investigated, which shown that the conceptual variation method will help students not only enhance their ability to correctly analyze the geometric construction, but also cultivate their personal perceptual ability.