The near band edge emission of ZnO is found to be tunable in ZnO/Bi2O3 nanocomposites via the changing accelerating voltages in cathodoluminescence test. Its intensity will be significantly increased when the accelerating voltage was larger than 10 KV, indicating a correspondingly change of dominant radioactive recombination in ZnO/Bi2O3 nanocomposites. It is suggested that the electron transfer between Bi2O3 and ZnO affects the dominant emission among the intrinsic emission of Bi2O3 and near band edge emission of ZnO. The higher accelerating voltage would be more likely to trigger the electron transfer and then enhance the near band emission of ZnO.