Thermal-response　amorphous　polymer　is　a　typical　soft　active　material　where　the　glass　transition　occurs　as　temperature　changes.　In　the　process　of　glass　transition,　the　amorphous　polymer　will　go　through　the　transitions　between　the　glassy　state　and　the　rubber　state.　Furthermore,　as　subjected　to　a　combining　load　of　the　mechanics　and　temperature,　the　materials　will　experience　deformation　and　glass　transition　simultaneously　and　exhibit　some　peculiar　macroscopic　response.　To　describe　this　behavior,　we　consider　the　evolution　of　natural　configurations　as　the　main　mechanism　for　such　thermo-mechanical　behavior,　and　develop　a　thermo-mechanical　constitutive　model　of　polymer　under　mechanical　and　thermal　loads.　As　application　the　proposed　model,　we　investigate　the　uniaxial　thermo-mechanical　behavior　of　the　soft　active　polymers.　It　is　shown　that　the　model　is　effective　for　describing　the　coupling　behavior　of　material　evolution　with　large　deformations　in　the　glass　transition　region.