Abstract: High-manganese steel has garnered significant attention for its exceptional low-temperature strength and toughness, and arc additive manufacturing technology has opened up broader application scenarios for this material. However, the use of arc additive manufacturing to produce high-manganese steel faces challenges such as coarse columnar grain structure and low yield strength. This study introduces NbC particles into the arc-based additive manufacturing process of high-manganese steel to investigate their effects on microstructure and mechanical properties. Results indicate that at room temperature, the tensile strength of NbC-particled high-manganese steel increases by 59 MPa, yield strength rises by 49 MPa, and total elongation improves from 46.5% to 50.8%. At low temperatures (−196 ℃), the tensile strength of NbC-added specimens increased by 145 MPa, yield strength rose by 92 MPa, and total elongation increased from 38.7% to 47.1%. This improvement stems from the addition of NbC particles, which refined the columnar crystal structure of the high-manganese steel, increased dislocation density, reduced the size and increased the density of deformation twins, and regulated the low-temperature stacking fault energy to suppress the martensitic phase transformation. This approach prevented the formation of brittle martensitic phases, ultimately achieving simultaneous enhancements in strength and ductility.