Abstract: Solar evaporation technology is considered to be a green and sustainable technology to alleviate water shortage. The substrate, as an important component of the solar evaporator, is a key factor affecting the evaporation efficiency. Hydrogels have become one of the research hotspots due to their wide source and easy preparation. In this paper, the research progress of the hydrogels in solar evaporators is reviewed. Hydrogel substrate materials, such as polyvinyl alcohol, chitosan, sodium alginate and cellulose are mainly introduced. The characteristics and applications of solar evaporators composed of different hydrogels and photothermal materials are analyzed. The corresponding suggestions for the hydrogel as the substrate of solar evaporator are given. It indicates that the fabrication of hydrogel substrate with more efficient contact area, the improvement of salt-resistant, antifouling and antibacterial properties and self-healing ability are important directions for the development of hydrogel-based solar evaporators.