Despite　the　promising　applications　of　hydrogels,　their　poor　mechanical　properties　still　greatly　limit　their　further　applications.　To　improve　the　mechanical　properties　of　hydrogels,　various　strategies　have　been　proposed.　Hydrogels　with　nanoparticle-crosslinked　polymer　networks　show　excellent　toughness,　self-recovery,　and　other　advantages,　and　thus　have　great　prospects　for　use　in　tissue　engineering,　artificial　muscles,　flexible　electronics,　and　other　fields.　There　have　been　experimental　and　theoretical　studies　of　its　damage.　However,　the　underlying　microscale　physical　mechanisms　have　not　been　fully　elucidated.　Herein,　we　established　a　physics-based　constitutive　model　to　describe　the　mechanical　behavior　of　nanoparticle-crosslinked　hydrogels　under　cyclic　loading.　The　deformation-induced　damage　and　the　rate-dependent　damage　were　explained　by　the　network　alteration　and　kinetics　of　chain　dissociation/association,　respectively.　The　kinetics　dissociation/association　theory　was　modified　considering　the　polymer　chains　that　wind　around　nanoparticles.　The　Mullins　stress　softening　and　recovery　during　cyclic　loading　were　described.　Cyclic　loading　tests　on　nanoparticle-crosslinked　hydrogels　were　carried　out　to　verify　the　proposed　constitutive　model.　It　is　demonstrated　that　the　model　can　well　describe　the　mechanical　behavior　of　nanoparticle-crosslinked　hydrogels　during　cyclic　loading.