Abstract: Two kinds of GaN PiN diodes were prepared to be the energy converters of betavoltaic batteries, and irradiated by ⁶³Ni and ³H radioactive sources. The I_sc was 5.4 nA and V_oc was 771 mV for ⁶³Ni source; the I_sc was 10.8 nA and V_oc was 839 mV for ³H source. These results show that their V_oc are far better than silicon diodes’, but their I_sc are poor. And there are some differences between the theory values and experiment results. There would be greatly improving space in electrical performance of betavoltaic isotope batteries with GaN diodes as the energy converters, if the dislocation could be reduced in GaN material producing process, the Ohmic contact could be prepared very well and the diodes configuration could be designed more optimizedly in the future.