Functionalized Fe/Cu bimetallic nanoparticles were prepared in this work for remediation of recalcitrant low-halogenated alkanes, for which the reducing capacity and process-enhancement control were investigated dealing with dichloromethane (DCM) as representative contaminant. Results show that vitamin B₁₂ significantly promoted the performance of Fe/Cu bimetal, since rate constant of DCM-reduction for Fe/Cu-B₁₂system (0.444h^-1) exhibited much higher than that of Fe/Cu system (0.018h^-1) or Fe-B₁₂ system (0.03h^-1), implying the synergistic effect of Cu and B₁₂ on electron-donating ability of zero-valent iron. Experiments were further conducted for process control, and results showed that 5% surface Cu-coverage and pH 9.5benefits better the catalytic reduction of DCM. Possible mechanism on catalytic performance of Fe/Cu-B₁₂ system was discussed referring to analysis on intermediate product as well as reduction kinetics. We speculated that the intermediate was prepared by dechlorination of target organic with B₁₂as an active electron acceptor on surface of Cu⁰, and then quickly decomposed to B₁₂ and hydrogenated halide, the catalytic process was completed under synergistic effects of Fe (electron donor), Cu and B₁₂.