Via　in　situ　TEM　tensile　tests　on　single　crystalline　copper　nanowires　with　an　advanced　tensile　device,　we　report　here　a　crystalline-liquid-rubber-like　(CRYS-LIQUE-R)　behavior　in　fracturing　crystalline　metallic　nanowires.　A　retractable　strain　of　the　fractured　crystalline　Cu　nanowires　can　approach　over　35%.　This　astonishing　CRYS-LIQUE-R　behavior　of　the　fracturing　highly　strained　single　crystalline　Cu　nanowires　originates　from　an　instant　release　of　the　stored　ultralarge　elastic　energy　in　the　crystalline　nanowires.　The　release　of　the　ultralarge　elastic　energy　was　estimated　to　generate　a　huge　reverse　stress　as　high　as　similar　to　10　GPa.　The　effective　diffusion　coefficient　(D-eff)　increased　sharply　due　to　the　consequent　pressure　gradient.　In　addition,　due　to　the　release　of　ultrahigh　elastic　energy,　the　estimated　concomitant　temperature　increase　was　estimated　as　high　as　0.6　Tm　(Tm　is　the　melting　point　of　nanocrystalline　Cu)　on　the　fractured　tip　of　the　nanowires.　These　factors　greatly　enhanced　the　atomic　diffusion　process.　Molecular　dynamic　simulations　revealed　that　the　very　high　reverse　stress　triggered　dislocation　nucleation　and　exhaustion.