The　basic　problem　of　eco-materials　is　how　to　judge　whether　a　kind　of　material　is　environmentally　friendly　or　not,　which　is　usually　evaluated　by　life　cycle　assessment.　Although　some　international　organizations,　such　as　ISO,　SETAC,　etc.,　have　given　detailed　specification　on　life　cycle　assessment,　life　cycle　assessment　is　still　in　developing　and　it　is　still　filled　with　dispute　in　some　important　environmental　problems,　for　example,　the　depletion　of　mineral　resources.　Recently,　for　a　purpose　to　get　more　objective　results　of　products＇　environment　performance,　a　new　assessment　model　exergy-based　model　of　life　cycle　assessment　combined　the　traditional　life　cycle　assessment　model　and　some　important　thermodynamic　concepts　(emergy,　exergy)　is　emerging.　The　basic　research　method　for　thermodynamics　is　to　study　the　interaction　between　system　and　environment.　If　considering　materials＇　life　cycle　as　a　system,　the　research　on　materials＇　environmental　performance　could　be　changed　to　the　research　on　the　interaction　between　the　system　of　materials＇　life　cycle　and　natural　environment.　Introducing　thermodynamic　theory　into　life　cycle　assessment　system　not　only　give　life　cycle　assessment　theoretical　basis　but　also　import　new　ideas　to　some　detailed　problems　in　LCA　like　the　depletion　of　mineral　resources.　(C)　2011　Published　by　Elsevier　Ltd.