By taking marine Pseudoalteromonas lipolytica (P. lipolytica) wild type strain (WT) and the genetically engineered P. lipolytica mutant strain with hmgA gene deletion (∆hmgA) as model strains, the influence of marine bacteria secreting pyomelanin on the corrosion behavior of 316L stainless steel in marine bacteria culture solutions was studied via electrochemical measurements, scanning electron microscopy (SEM), laser confocal microscopy (CLSM) and X-ray diffraction (XRD). It was proved that WT strain did not cause corrosion of the stainless steel, correspondingly a compact passivation film may form on the steel surface in the medium containing WT. While the ∆hmgA strain will secrete pyomelanin and induce formation of mineralization sites on the stainless-steel surface, thus destroying the formed passivation film and further causing serious pitting corrosion. In bacterial pyomelanin solution, the stainless steel will also be suffered from pitting corrosion, however, a rather intact passivation film can still be formed on the steel surface due to that no bacteria may be involved to the process. In general, this study revealed that the corrosion mechanism of stainless steel in the environments containing pigmented bacteria and the influence of pyomelanin on passivation film formation and pitting development.