Copper　nanowire　is　a　potential　material　used　as　interconnect　or　component　in　the　micro/　nano　devices　because　of　its　high　electrical　and　thermal　conductivity.　Therefore,　quantitative　measurement　of　mechanical　properties　of　Cu　nanowire　is　essential　to　the　development　of　novel　micro/nano　devices.　Here,　in　situ　3-point　bending　experiment　is　performed　to　measure　the　elastic　properties　of　Cu　nanowire　using　a　SEM/SPM　hybrid　system.　The　experimental　results　show　that　the　elastic　modulus　of　Cu　nanowire　is　significant　size　dependency　in　the　research　range.