The work aims to provide theoretical basis for the research of corrosion laws and microbial corrosion prevention in the marine environment by studying the corrosion behavior of marine engineering steel DH36 in Vibrio natriegens, Bacillussp. and Vibrio natriegens-Bacillus sp. mixed species. The corrosion morphologies and electrochemical characteristics of DH36 steel in the different corrosion systems were tested by the scanning electron microscope, energy dispersive spectrometer, electrochemical testing equipment and other methods. SEM images showed that there were large amounts of Bacillus sp. adhered on the surface of DH36 steel. The mixed layer of biofilm and rust layer in the corrosion system of Vibrio natriegens and Vibrio natriegens-Bacillus mixed species had lots of cracks and crevices, thus leading to poor compactness. The electrochemical results indicated that there were two time constants existed in the surfaces of the samples, and the inductive impedance characteristics appeared in low frequency. In the presence of Bacillus sp., the corrosion rate increased at beginning and then decreased with increasing immersion time. The corrosion rate in Vibrio natriegens corrosion system was between those of Bacillus sp. and the mixed species corrosion system after 3 d of immersion. Compared with the single-bacteria corrosion system, open circuit potential in Vibrio natriegens-Bacillus corrosion system was the lowest during immersion time and corrosion rate was the highest after 7 d of immersion, which was 13.53 μA/cm2. Bacillus sp. shows the corrosion inhibition effect in the late immersion stage. The corrosion rate increases in Vibrio natriegens and Vibrio natriegens-Bacillus corrosion system because of the corrosive metabolites and porous mixed layer. Meanwhile, the corrosion behavior of DH36 in the Vibrio natriegens-Bacillus sp. system is more serious.