1609 Galileo used a telescope to observe celestial bodies, which played a role in increasing the luminous flux density and expanding the viewing angle of the telescope, and created modern optical astronomy. He not only drew a map of the moon, observed the profit and loss of Venus, but also saw sunspots, and determined that the Milky Way was made up of stars. With the development of productive forces and the progress of science and technology, the precision of optical telescopes is getting higher and higher, and the aperture is getting larger and larger, so that new celestial bodies are constantly discovered and new astronomical phenomena are observed. Because three physical methods (optics, photometry and photography) have been applied in the field of astronomy, the foundation of astrophysics branches such as solar physics and stellar physics has been gradually laid. Since Kirchhoff explained the origin of absorption line, fractional optics has played a very important role in celestial observation. Through observation and research, people can not only measure the physical characteristics of celestial bodies such as temperature, density and pressure, but also get the data of celestial chemical composition. The branch of modern astronomy, especially theoretical astrophysics, has developed faster under the influence of theoretical physics. The monochromatic observation of the chromosphere of the Sun, the discovery of the magnetic field of sunspots, the discovery of the relationship between the period and luminosity of Cepheid variables, the establishment of Herro diagram, the proof of interstellar extinction, the proof that galaxies are composed of stars and interstellar matter, the red shift of the spectral lines of galaxies, and the discovery of the rotation of the Milky Way, the rotation of stars, the Star Association, the star chain and even Uranus rings are all great achievements of optical astronomy. In recent decades, the rise of radio astronomy, the revival of infrared astronomy, the birth of ultraviolet astronomy, X-ray astronomy and gamma-ray astronomy have made modern astrophysics enter the forefront of natural science. However, optical astronomy cooperates with the above sub-disciplines and continues to contribute to the development of related disciplines.