Since the outbreak of COVID-19, online teaching has been widely practiced. Ensuring the quality and efficiency of online teaching has become an important research topic. Teachers’ views of online teaching directly affect the quality of instruction. The study aimed to understand whether there are differences in the basic perceptions of online teaching among teachers in different disciplines. Through a web-based questionnaire, the researchers surveyed 198 teachers from different disciplines about their perceptions of online teaching. The research method was a convergent mixed-method design. SPSS 22.0 was used to analyze quantitative data, and qualitative data were analyzed using NVivo 11. The results showed significant differences in the attitudes of teachers to adopt online teaching as the norm in different disciplines. Social science teachers preferred online education not to be the norm, while natural science teachers preferred online education to be the norm. In addition, there was little difference in the perceptions of online teaching among teachers of different disciplines. Most of them pointed out the problem of interactive communication in online teaching and gave suggestions about it. Online teaching has value, but there is still much room for improvement. It is necessary to strengthen the construction of facilities for online education, consider the characteristics of disciplines, and train teachers in teaching methods, learning psychology, and technology.