The corrosion behavior of Q235 steel by Iron Bacteria (IB), Sulfate-reducing Bacteria (SRB) and Total General Bacteria (TGB) in sedimentary water of storage tank from an aromatics plant was investigated mainly by static hanging piece method, potentiodynamic polarization curve and hysteresis loop method. The results showed that the interaction of IB, SRB and TGB accelerated the corrosion rate of Q235 steel. The corrosion current density of Q235 steel electrode in IB, SRB and TGB solution was higher than that in the sterile solution, and the corrosion potential shifted in negative direction. IB, SRB and TGB reduced the corrosion resistance of Q235 steel. The corrosion of Q235 steel in the mixture of IB, SRB and TGB was more serious than in a single microbial system. The presence of IB, SRB and TGB made the pitting occur easily.