The Cu−15Ni−8Sn alloy wire with a nano-layered structure was fabricated using directional solidification techniques and a multi-stage thermomechanical treatment. A systematic investigation was conducted on microstructure evolution and its impact on mechanical properties. After aging at 400 °C for 0.25 h, the ultimate tensile strength of the alloy reaches 1509 MPa, >200 MPa higher than that of the alloy after single thermomechanical treatment. Furthermore, grain refinement and heightened á111ñ fiber texture are identified as key factors contributing to the enhancement of the mechanical properties of the alloy. These findings highlight the importance of multi-stage thermomechanical treatment on microstructure evolution and mechanical properties of Cu−15Ni−8Sn alloy.