Soft　adaptable　materials　and　structures　that　change　their　shapes,　volumes　and　properties　in　response　to　surrounding　environment　are　important　and　ideal　for　scientific　and　engineering　applications.　Existing　soft　gels　exhibit　a　dramatic　volumetric　swelling　deformation　when　immersed　in　solution.　Developing　an　innovative　material　system　that　can　undergo　large　and　actively　negative　swelling　deformation　driven　by　solution　is　an　interesting　challenge.　In　this　work,　a　water-driven　mechanical　metamaterial　with　negative　swelling　is　designed　and　fabricated　based　on　the　coupled　responses　of　the　swelling　of　hydrogels　and　deformation　characteristics　of　chiral　metamaterials.　The　constructed　metamaterial　utilizes　deformation　characteristics　of　4D　printed　composite　structure　to　convert　the　swelling　deformation　of　the　hydrogel　into　a　bending　deformation　of　flexible　ligaments,　resulting　in　a　volume　reduction　of　the　entire　metamaterial.　Activated　by　surrounding　solution,　the　metamaterial　can　achieve　large　and　adjustable　effective　negative　swelling　behaviors　with　the　desired　isotropic　characteristics.　Based　on　experimental　data　and　finite　element　simulation　results,　the　customized　metamaterials　can　be　implemented　to　produce　the　desired　negative　swelling　deformation　by　adjusting　the　lattice　geometry　and　microstructural　parameters.　These　design　concepts　exploit　the　capabilities　of　existing　soft　materials　and　have　great　potential　in　a　variety　of　applications.