Active　control　over　the　optical　response　has　been　investigated　extensively,　which　is　highly　required　in　next-generation　photonic　devices.　Here,　we　report　a　core-shell　nanostructure　combined　with　the　plasmonic　nanostructure　with　an　active　phase　change　material,　termed　as　Au@GST,　where　the　individual　Au　nanoparticle　is　wrapped　by　isolated　active　Ge2Sb2Te5　(GST)　tuning　medium　as　the　shell.　We　demonstrate　the　active　control　of　optical　response　by　the　simultaneous　control　of　size　and　crystallization　degree　of　the　phase　change　shell　within　each　isolated　core-shell　nanostructure.　The　hetero-nanostructures　are　synthesized　by　direct　sputtering　of　stoichiometric　GST　on　Au　nanoparticles　with　different　sizes　based　on　a　seeding　effect　of　the　metal　nanostructures.　The　tunable　optical　response　is　enabled　by　inducing　the　GST　shell　phase　states　between　amorphous　and　crystalline　phases　through　thermal　annealing,　accompanied　by　high　optical　contrast.　We　demonstrate　the　tunable　optical　response　(from　570　to　630　nm)　of　the　hetero-nanostructures　by　tailoring　the　GST　shell＇s　optical　property.　The　experimental　results　show　that　the　optical　response　of　the　Au@GST　core-shell　hetero-nanostructures　exhibits　high　sensitivity　to　the　size　of　the　nanoparticles　(GST　thickness　and　Au　diameter).　The　simulation　results　are　in　good　agreement　with　the　experiments.　This　confirms　the　dominant　role　of　the　phase　states　on　the　optical　modulation.　Furthermore,　this　study　provides　a　single-step　and　lithography-free　3D　printing　process　to　arrange　the　hybrid　Au@GST　core-shell　nanostructures　in　a　large　area　deliberately,　giving　additional　flexibility　to　control　over　the　architecture　and　geometry.　Such　Au@GST　core-shell　hetero-nanostructures　have　the　potential　for　active　control　of　nanophotonic　devices,　such　as　super-resolution　imaging　and　programmable　metasurfaces.