The invention discloses a method for the in-situ remediation of heavy metal hexavalent chromium-contaminated soil. According to the method, by using the advantages of a microbial fuel cell (MFC), an anode assembly and a cathode assembly (a diaphragm is arranged between the anode assembly and the cathode assembly) is embedded in the contaminated soil, the anode assembly locally utilizes organic matters in the soil as fuel, generated electronics reach the cathode assembly by virtue of anodes and leads, heavy metal hexavalent chromium adsorbed on the cathode assembly is reduced, and thus the degradation and the transformation of heavy metal hexavalent chromium contaminants in the soil are promoted, and the in-situ remediation of the heavy metal hexavalent chromium-contaminated soil is realized. By adopting an in-situ remediation process, the method has the advantages of high removal efficiency, low cost, good safety, no need of ventilation and energy consumption, capability of recycling and no secondary pollution because the anode assembly and the cathode assembly can be combined and optimized according to the actual conditions, has the great importance in remediating the heavy metal hexavalent chromium-contaminated soil, has a wide application prospect in fields of resources and environments such as the remediation of the heavy metal hexavalent chromium-contaminated soil, and the like.