The present invention provides an oligotrophic sulfate reducing bacterium. The oligotrophic sulfate reducing bacterium is classified and named as desulfovibrio vulgaris EM2, a preservation unit is China Center for Type Culture Collection, an address is Wuhan University, Wuhan, China, a preservation date is November 1, 2017 and a preservation number of CCTCC M 2017645. The bacterium can conduct anaerobic reduction of sulfate radicals into negative divalent sulfur ions under an oligotrophic concentration, and can be used for repairing heavy metal pollution in riverway bottom sediment.