Abstract: Natural exposure test and accelerated exposure test with 5% salt spray were carried on Q235 steel in atmospheric environment for 180 days. The macro/micro morphology changes, weight loss and degradation of different mechanical indices with corrosion ratio were analyzed and compared to investigate the effect of salt spray on early corrosion behavior of Q235 steel in atmospheric environment. The results show that salt spray accelerates the corrosion process of rust-layer shedding and crack extension of steel. The corrosion depth and corrosion rate are tenfold increased by salt spray compared with natural exposure test, but its accelerating effect decreases with exposure time increasing.Salt spray intensifies the time-varying effect of mechanical property degradation, but it reduces the weakening effect of corrosion ratio on mechanical properties, among which the influence on elastic modulus is the greatest.