A　molecular　network　constitutive　model　is　proposed　in　this　study.　Based　on　the　concept　of　molecular　network　decomposition,　the　molecular　network　was　decomposed　into　a　James-Guth　3-chain　network　model　and　an　Arruda-Boyce　8-chain　network　model.　Considering　that　the　single　molecular　chain　of　rubber　is　constrained　by　the　surrounding　molecular　networks,　the　3-chain　model　and　the　8-chain　model　were　consequently　modified　using　the　tube　theory.　The　proposed　model　contains　four　material　parameters　that　were　determined　by　fitting　the　uniaxial　tensile　test　data　from　rubber-like　materials,　and　the　values　of　these　parameters　were　utilized　to　determine　the　pure　shear　and　the　biaxial　extension.　The　proposed　model　agrees　well　with　the　experimental　data　and　can　predict　the　test　results　of　experiments　performed　under　the　conditions　of　pure　shear　and　equi-biaxial　deformation　with　acceptable　accuracy.