The author explains astrophysics from the perspective of physics as well as of astronomy, with special attention to the important role of gravity in astrophysics. Either in a general university or a particular college of science and technology, astronomy education should be necessary for both sciences and humanities, and astrophysics is a vital ingredient in teaching astronomy. The course of astrophysics at Peking University is introduced. Finally, this article concludes with teaching cases such as the muon-generation in air shower, the chirp mass and the accelerating universe.