With the rapid development of the economy and technology, heavy metal industrial wastewater has caused a great impact on the environment and has gradually become a global concern. As a new type of environmentally friendly adsorption material, the gel has a good adsorption capacity because of its special network structure, so it can be used in wastewater treatment, water purification, and other fields. In this paper, the structure, classification, and application direction of gels are discussed in detail.