Single-crystal　superalloy　is　the　key　material　of　turbine　blade　and　hot　end　parts　in　aerospace　field.　The　second　generation　nickel-based　single　crystal　superalloy　has　been　widely　used　because　of　its　low　cost　and　excellent　high　temperature　properties.　At　present,　the　research　on　microstructure　of　superalloys　at　high　temperature　mainly　depends　on　SEM　and　TEM　observation　after　heating　and　loading　experiment.　However,　such　kind　of　work　lacks　real-time　characterization　capabilities.　Carrying　out　in　situ　experiments　has　an　important　significance　for　understanding　the　real　time　deformation　behavior　and　microstructure　evolution　of　superalloys.　Therefore,　the　development　of　an　in　situ　high　temperature　(above　1000　degrees　C)　mechanical　testing　equipment　for　SEM　faces　huge　challenges.　In　this　work,　high　temperature　tensile　experiment　at　1150　degrees　C　of　a　second　generation　single　crystal　nickel-based　superalloy　were　carried　out　by　means　of　a　self-developed　in　situ　heating　tensile　platform　which　can　used　in　SEM.　A　high　quality　experimental　data　and　serial　SEM　images　were　obtained　in　the　course　of　tensile　testing　at　1150　degrees　C.　The　analysis　of　force-displacement　curve　shows　that　the　yield　strength　and　fracture　strength　of　the　specimen　are　580　and　620　MPa,　respectively.　The　sequential　SEM　images　during　this　research　confirm　that　there　is　no　obvious　shape　and　size　change　for　gamma　and　gamma＇　during　the　elastic　deformation,　and　microstructure　changing　during　plastic　stage　is　mainly　due　to　gamma　phase　widening　which　is　parallel　to　the　stress　axis.　The　results　show　that　the　original　micro-voids　of　samples　are　the　weakness　in　high　temperature　tensile　test　at　1150　degrees　C,　the　fracture　direction　is　almost　perpendicular　to　the　stress　axis,　the　crack　propagated　by　passing　the　gamma＇　phase　and　through　in　the　gamma　phase,　and　ultimately,　temperature　and　stress　induced　adjacent　holes　connection　leading　to　the　sample　fracture.