Photopolymerization as an energy-saving and environment-friendly technology has been applied in many fields and developed continuously since the middle of the 20th century. Today, photopolymerization technology is ubiquitous in every aspect of our lives. This review starts from the principle of photopolymerization reaction, introduces the process of photopolymerization, initiation mechanism of photoinitiators and three kinds of polymerization methods according to the wavelength of irradiation source. Subsequently, review focuses on the application of photopolymerization technology in thiol-based click reaction, 3D printing, photoresist, hydrogels and other fields, so as to demonstrate its irreplaceable role in the present.