Currently　existing　extensometer　may　not　completely　correspond　with　the　requirement　of　precision　and　linearity　in　the　measurement　of　enormous　structure＇s　strain.　The　objective　of　this　research　is　to　describe　a　new　structure　of　high　precision　extensometer　sensor.　An　half　of　an　annular　chip　serves　as　the　elastic　element　of　the　new　extensometer.　Theoretical　analyses　and　discussions　about　the　accuracy　and　linearity　of　this　new　elastic　element　are　conducted.　Based　on　the　oil　sucking　machine,　the　new　structure　of　high　precision　extensometer　sensor　is　installed　to　measure　the　micro　strain　as　an　experiment.　Statics　calculation　examine　that　the　deflection　of　measuring　terminal　shows　linear　relationship　with　the　strain　of　the　elastic　element　in　certain　position.　Theoretically,　the　feasibility　of　a　series　of　elastic　elements　is　discussed.　The　results　can　provide　reference　value　and　significance　in　the　innovation　and　design　of　industrial　measurement.