An　in　situ　nanoindentation　test　system　was　established　by　combining　atomic　force　microscope　(AFM)　and　scan　electron　microscope　(SEM).　This　system　enabled　the　indentation　experiment　using　the　AFM　cantilever　with　Cube　corner　diamond　indenter,　and　acquired　the　curve　of　load　versus　displacement.　The　experimental　process　can　be　observed　in　real　time　by　in　situ　SEM　simultaneously.　A　mechanical　property　testing　method,　based　on　the　AFM　cantilever　loading　curve　and　the　in　situ　SEM　indentation　of　images　analysis,　was　well　developed.　The　hardness　and　elastic　model　of　the　plastic　thin　film　were　obtained　by　measuring　the　maximum　loading　during　the　indentation　and　the　residual　area　of　the　indentation　by　measuring　SEM　image.　This　method　was　demonstrated　by　conducting　the　indentation　experiment　on　the　sliver　film　deposited　on　the　Si　substrate　using　magnetron　sputtering.　Furthermore,　the　experiment　conducted　by　the　Nanoindenter　G200　was　presented　here　for　comparison.　The　results　show　that　the　in　situ　AFM　indentation　possesses　higher　resolution　of　loading　and　displacement,　and　can　achieve　the　indentation　experiment　scaled　from　nN　to　mN　of　the　applied　load.　The　hardness　of　the　plastic　thin　film　can　be　obtained　by　measuring　the　residual　area　of　indentation.　The　pile-up　effect　of　the　soft　film　deposited　on　the　hard　substrate,　which　exists　in　the　Oliver-pharr　method,　can　be　reduced　by　SEM　image　analyses　of　residual　area　and　the　calculation　has　a　higher　testing　accuracy　and　reliability　as　well.