The spatial distribution and environmental implication of sulfate-reducing bacteria (SRB) were investigated in the coastal sediments from Zhanjiang Bay and Leizhou Bay, China. The SRB existed in all over the sediments from Zhanjiang Bay and Leizhou Bay, and showed a high spatial variation. The counts of SRB in Zhanjiang Bay are much more than those in Leizhou Bay because Zhanjiang Bay was much more affected by human activity, whereas Leizhou Bay was protected as habitats. SRB counts increase from the outer area to inner in Zhanjiang Bay, mainly resulting from the fact that the inner area are influenced by anthropogenic frequency and has a low oxidation-reduction potential (Eh), whereas outer area is little influenced by anthropogenic and has a high Eh. Total organic carbon (TOC) content was not significantly positively correlated with SRB, but the tendency in the whole was that where there existed the higher TOC content, there would be the more counts of SRB. There was no significant relationship between SRB and particle size distribution (PSD) and Eh, whereas acid volatile sulfide (AVS) and the concentration of Fe (II) were significant positive correlated with SRB. It can be concluded that the distribution of SRB closely related to the concentration of Fe (II) and is an important cause for the spatial distribution of AVS, which is regarded as one of the key indicator of heavy metal bioavailability.