Abstract: Taking the national first-class undergraduate course “structural mechanics” in our university as an example, this paper summarized the construction process of online and offline mixed first-class courses, and introduced the online and offline mixed teaching practice which combined traditional classroom, online classroom, offline overturn classroom and MOOC classroom, and analyzed the effect of online and offline mixed teaching based on the overall number of learners, course assessment results and course evaluation, in order to provide reference for the construction of related courses.