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The fatigue pre-cracking 304 stainless steel (SS) specimens with lengths of 1.002 mm (L-crack) and 0.575 mm (S-crack) were prepared. Their corrosion behavior was studied by electrochemical noise (EN) in 4 mol/L NaCl + 0.01 mol/L Na_2S_2O_3 solution under slow-strain-rate-testing (SSRT) conditions. Moreover, the characteristics of L-crack’s surface morphology and potential distribution with scanning Kelvin probe (SKP) before and after SSRT were also discussed. Compared with S-crack, L-crack is propagated and the features of crack propagation can be obtained. After propagation, the noise amplitudes increase with increasing stress and accelerating corrosion, the white noises at low and high frequencies (W_L and W_H) of the later stage are one order of magnitude larger than that at early stage in the current power spectral densities (PSDs). The potential PSDs also increase, but W_H disappears. In addition, the crack propagation can be demonstrated according to variation of probability distribution, surface morphology and potential distribution.