Over　the　past　few　years,　with　the　development　of　global　industry　and　the　increase　of　population,　the　shortage　of　freshwater　resources　has　prompted　people　to　conduct　in-depth　research　on　advanced　water　treatment　and　water　harvesting　technologies.　As　a　polymer　material　with　a　three-dimensional　network　structure,　hydrogel　has　been　widely　used　in　water　resources　harvesting　and　treatment　due　to　its　excellent　water　absorption,　water　retention,　and　adsorption　properties.　In　this　review,　we　first　introduced　several　synthetic　routes　of　hydrogel　materials,　including　chemical　cross-linking,　physical　cross-linking　and　dual　cross-linking,　and　discussed　the　advantages　and　disadvantages　of　several　synthetic　methods.　Then,　we　emphasized　the　water　absorption　and　desorption　mechanism　of　hydrogels　and　related　influencing　factors.　Next,　we　described　the　latest　research　progress　of　hydrogel　materials　in　detail　as　a　platform　for　atmospheric　water　harvesting,　seawater　desalination　and　wastewater　treatment　in　recent　years.　Finally,　we　discussed　the　shortcomings　and　future　orientation　of　water　purification　and　water　treatment　systems　based　on　hydrogel　materials.