In　this　work,　pure　Cu　with　excellent　strength　and　ductility　(UTS　of　271　MPa,　elongation　to　fracture　of　43.5%,　uniform　elongation　of　30%)　was　prepared　using　cold　spray　additive　manufacturing　(CSAM),　realizing　a　breakthrough　in　the　field.　An　in-depth　investigation　was　conducted　to　reveal　the　microstructure　evolution,　strengthening　and　ductilization　mechanisms　of　the　CSAM　Cu,　as　well　as　the　single　splats.　The　results　show　that　the　CSAM　Cu　possesses　a　unique　heterogeneous　microstructure　with　a　bimodal　grain　structure　and　extensive　infinitely　circulating　ring-mounted　distribution　of　twinning.　Based　on　the　single　splat　observation,　the　entire　copper　particle　forms　a　gradient　nano-grained　(GNG)　structure　after　high-speed　impact　deposition.　The　GNG-structured　single　splat　serves　as　a　unit　to　build　the　heterogeneous　microstructure　with　bimodal　grain　distribution　during　the　successive　deposition　in　CSAM.　The　results　also　show　that　CSAM　can　achieve　synergistic　strengthening　and　ductilization　by　controlling　the　grain　refinement　and　dislocation　density.　This　work　provides　potential　for　CSAM　technique　in　manufacturing　various　metallic　parts　with　the　desired　combination　of　high　strength　and　good　ductility　without　additional　post-treatments.　©　2022