This work aimed to in-situ monitor the atmospheric corrosion of steels exposed to Zhoushan offshore environment by using electrochemical noise (EN) technique. A portable EN monitoring system was established and two electrochemical probes (named as Q235B and T91) were designed. Experimental results indicated that the noise resistance of T91 steel was higher than that of Q235B steel, revealing that the corrosion resistance of T91 was higher than that of Q235B. A 60-day monitoring result indicated that the noise resistance was well correlated with the weight loss data. Wavelet analyses results of EN data indicated that Q235B underwent uniform corrosion and T91 suffered from localized corrosion, which was further confirmed by the surface observation. It is concluded that EN can be used as a new method to identify the corrosion form and corrosion resistance in atmospheric conditions.