The large-scale online teaching amid the pandemic triggered increasing concern over online teaching management and quality assurance. Take the theory of Total Quality Management (TQM) as guidance, a Chinese higher education institution (CHEI) built a multi-level, multi-link, and multi-dimensional teaching quality monitoring system (Online Teaching Quality Assurance Measures) with full participation, whole process, and all-round development by innovating teaching quality management and monitoring mechanism, aiming to ensure the continuous improvement of talent training quality to realize the sustainable development of application-oriented undergraduate universities with quality improvement as the core. The effectiveness of online teaching quality was demonstrated through the Questionnaire of Student Evaluation of Online Teaching Faculty and students' academic performance (GPA) before and after the implementation of Online Teaching Quality Assurance Measures, guided by the principles of Total Quality Management theory. The results indicated that Online Teaching Quality Assurance Measures have a series of positive effects on online teaching in CHEI, and systematically guide online instructors as evidenced by outstanding ratings and feedback in course evaluations and students' academic performance. This study also revealed that CHEI's online teaching is facing some challenges, especially in the effort to promote learning interaction and teaching cooperation. The study underscored the importance of continuous improvement and provided some interventions in enhancing online educational practices, aligning with TQM principles. The findings are expected to make an important contribution to the field of online teaching quality management in higher education.