Based on the in-depth analysis of MOOC and "flipped classroom" teaching mode, the paper discusses the trend of applying "MOOC + flipped classroom" teaching mode in university teaching, clarifies its positioning as a teaching method and mode, and points out that "flipped classroom" teaching mode not only emphasizes students' subjectivity, but also confirms teachers' leading role in the whole teaching process. The successful practice of "MOOC + flipped classroom" teaching mode in theoretical mechanics course of Guangzhou University shows that students' willingness of autonomous learning has a very important impact on the teaching effect under this mode, the biggest difficulty in implementing this teaching mode lies in the difference in the effect of before class autonomous learning and knowledge base, and teachers' control of each teaching link is the fundamental guarantee for the effectiveness of "MOOC + flipped classroom" teaching mode.