A knowledge gap exists regarding the faculty's dynamic selection and modification of emotion regulation strategies to reduce negative emotions in synchronous teaching. This study conducted semi-structured interviews with 16 teachers at higher education institutions in China, focusing on their handling of the negative emotions that arose from poor teacher-student interactions. Technology-induced and student-induced behaviour problems are two primary causes of faculty's negative emotions. The problem-focused emotion regulation strategy effectively reduced faculty's negative emotions when facing the former. In handling student-induced negative emotions, the problem-focused strategy was only occasionally sufficient. The ownership of synchronous teaching provides faculty with continuous agency to reflect on teaching challenges. The outcome of this reflection enables faculty to alter emotion regulation strategies and ultimately reduce negative emotions without compromising students' rights. We propose that critical reflection that challenges underlying assumptions (e.g., double-loop learning) can effectively mitigate negative emotions while ensuring equitable online education.