To meet the stringent property demands of aviation fasteners， the development of aviation-grade 303Se free-cutting austenitic stainless steel cold-drawn bars was undertaken. Based on SAE AMS5640， the chemical composition was designed and refined by precisely controlling key elements to/%：≤0.03C ，0.03-0.06N ，0.30Se， 0.13P， to secure an optimum balance between machinability and mechanical strength. According to hot-ductility test results， the reheating soak temperature 1 220 ℃-1 260 ℃， the start rolling temperature 1 120 ℃-1 200 ℃， the finish rolling temperature ≥ 1

000 ℃ was established to roll the wire. the wire was cooled with water to room temperature after wire rod laying，and then cold drew with deformation of 15%-25%， to the

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13.7 mm 303Se cold-drawn bars. The final product exhibits an ultimate tensile strength of 937 MPa （target range 897 MPa-1 030 MPa） ，a reduction of area of 58 % with hardness of 171 HBW （solution-treated target range 140 HBW-255 HBW）. The microstructure is composed of single-phase austenite （no ferrite detected by XRD），with the grain size of grade 7 and the overall non-metallic inclusion rating of ≤ 3.0. All chemical， mechanical and metallographic requirements of the standard are satisfied， providing excellent processing stability and service reliability. The results offer a technical foundation for the localization of high-performance stainless steels for aviation fasteners.