High strength-high corrosion resistance wire was developed for automotive suspension coil springs. By adding Nb, B and optimizing C, Si, Cu, tensile strength has increased by 10% and the grain size reduced to 1/3 compared to conventional spring wire. On the other hand, to improve the limitations of the existing test mode, new corrosion-fatigue test was developed. As a result, vehicle damage modes were reproduced exactly. Through newly developed corrosion-fatigue test and the actual driving test, duration of fatigue life has been confirmed to be improved up to 20%.