The cleaning and restoration of cultural relics is a delicate and challenging task. Many cultural relics not only have rough and pitted surfaces, but also exhibit strong sensitivity to organic or water-based solvents. Traditional cleaning methods cannot achieve good cleaning results and may even cause damage to cultural relics. Hydrogel materials have attracted the attention of conservation and restoration workers because they can effectively control solvent release and have a good cleaning effect in removing stains on the surface of cultural relics. The characteristics of traditional cleaning methods and hydrogel cleaning methods are compared and analyzed, with the structure and classification of hydrogels summarized, and the actual cultural relics cleaning cases of different types of hydrogels listed. Finally, the current problems and future development trends of hydrogels are proposed.