To enrich biocathode having higher activity and decrease the operating cost, the effects of the applied voltages on the electroactivity of biocathode and COD concentration were investigated in glucose-fed SCMMEC,respectively. The results with biocathodes enriched under 0.2V、0.3V and 0.5V showed that：there was no evident difference in electroactivity,and the 0.3V-biocathodes having the highest electroactivity were still the current-limiting electrodes.This suggested that using power source with lower stability not only could decrease SCMMEC’s cost,but also doesn’t impact the performance of biocathode.The selection of applied voltage should also consider the influent COD according to the influent COD-applied voltage- current density tests, lower applied voltage for lower COD concentration, and rather than vice versa.