In　this　paper,　a　model　is　presented　to　correlate　and　predict　the　swelling　behavior　of　hydrogels　in　aqueous　solutions　of　electrolytes.　The　model　is　a　combination　of　VERS-model,　＂phantom　network＂　theory　and　＂free-volume＂　contribution.　The　VERS-model　is　used　to　calculate　Gibbs　excess　energy;　＂phantom　network＂　theory　to　describe　the　elastic　properties　of　polymer　network,　and　＂free-volume＂　contribution　to　account　for　additional　difference　in　the　size　of　the　species.　To　test　the　model,　a　series　of　N-isopropylacrylamide　based　hydrogels　are　synthesized　by　free　radical　polymerization　in　oxygen-free,　deionized　water　at　25degreesC　under　nitrogen　atmosphere.　Then,　the　degree　of　swelling　of　all　investigated　gels　as　well　as　the　partition　of　the　solute　between　the　gel　phase　and　the　surrounding　coexisting　liquid　phase　are　measured　in　aqueous　solution　of　sodium　chloride.　The　model　test　demonstrates　that　the　swelling　behavior　correlated　and　predicted　by　the　model　agrees　with　the　experimental　data　within　the　experimental　uncertainty.　The　phase　transition　appeared　in　the　experiment,　and　the　influences　of　the　total　mass　fraction　of　polymerizable　materials　xi(gel)　as　well　as　the　mole　fraction　of　the　crosslinking　agent　y(CR)　on　the　swelling　behavior　of　IPAAm-gels　can　also　be　predicted　correctly.　All　these　show　the　potential　of　such　model　for　correlation　and　prediction　of　the　swelling　behavior　of　hydrogels　in　aqueous　solutions　of　electrolytes.