In the face of the complex, severe and changing epidemic situation, the teaching has changed from offline to online, and from online to online and offline mixed teaching. In view of the change of teaching mode and the actual situation of students, we carefully carry out high-quality teaching design based on the concept of OBE, reasonably design three teaching links before class, during class and after class, appropriately set the difficulty, breadth and depth of the course, and combine professional knowledge of chemical principles with curriculum ideology and politics to make the class more exciting. Measures to achieve substantial equivalence of online and offline learning were explored and practiced, providing reference for the teaching reform of chemical principles in colleges and universities under the post-epidemic background.