In order to ensure the quality of online mixed teaching of structural mechanics, promote students'' active learning and improve the quality of personnel training during the outbreak of NCP. Based on the teaching syllabus and training objectives of structural mechanics, choose Learning Tong and Dingding software as the teaching platform, optimize the allocation of teaching resources, innovate classroom teaching design, through moral education, learning guidance, learning exploration, teaching improvement and teaching innovation, the online mixed classroom teaching effect is guaranteed. through the four modules of homework, test, interactive discussion and sign in, the whole process of teaching management is fair and just, and the results are true and effective.The results show that the students have a positive attitude towards learning, their enthusiasm for active learning is significantly improved, their usual performance is better, and the final paper performance is good, basically achieving the goal of substantially equivalent online and offline teaching effects.Teachers'' diligence, students'' exertion, the online mixed teaching mode of structural mechanics courses can guarantee and improve the quality of student training.