Wire-arc　additive　manufacturing　(WAAM)　is　extensively　employed　in　remanufacturing　owing　to　high　efficiency　and　cost-effectiveness.　However,　it　often　results　in　coarse　grain　structures　and　considerable　residual　stress,　ultimately　deteriorating　mechanical　properties　and　fatigue　life　of　remanufactured　components.　This　study　addresses　this　issue　by　utilizing　a　customized　in-situ　hot　rolling-assisted　WAAM　(HR-WAAM)　system,　specially　designed　for　rotational　components,　to　remanufacture　a　motor　shaft　using　a　high-strength　low-alloy　steel　wire.　The　rolling　temperature　was　maintained　within　the　ferrite　phase　region.　Comparative　analyses　of　single-layer,　double-layer,　and　multi-layer　samples　were　conducted　to　uncover　the　combined　effects　of　in-situ　hot　rolling　and　thermal　cycling　on　microstructure　and　mechanical　properties.　In-situ　hot　rolling　introduces　substantial　low-angle　grain　boundaries　and　dislocations,　serving　as　nucleation　sites　for　recrystallization.　Thermal　cycling　during　subsequent　deposition　not　only　provides　necessary　activation　energy　to　enhance　grain　boundary　mobility　and　thus　promotes　recrystallization,　but　also　induces　various　solid-state　phase　transformations　to　facilitate　grain　refinement　and　microstructural　homogenization.　An　optimal　processing　window　was　identified　with　a　rolling　temperature　of　600-700　degrees　C　and　23　%　rolling　strain.　The　yield　strength　of　HR-WAAM　low-alloy　steel　increased　from　604　MPa　to　786　MPa　while　maintaining　an　elongation　of　20　%,　comparable　to　that　of　WAAM　samples.　Moreover,　the　high-cycle　fatigue　strength　substantially　increases　from　428　MPa　to　501　MPa.　These　enhancements　primarily　result　from　grain　refinement　and　the　introduction　of　compressive　residual　stress.　This　work　demonstrates　that　HR-WAAM　can　effectively　tailor　microstructures　to　achieve　strength-ductility　synergy　and　provides　a　technical　reference　for　its　application　in　shaft　remanufacturing.