Gallium Nitride (GaN) PIN betavoltaic nuclear batteries (GB) are demonstrated in our work for the first time. GaN films are grown on sapphire substrates by metalorganic chemical vapor deposition (MOCVD), and then GaN PIN diodes are fabricated by normal micro-fabrication process. Nickel with mass number of 63 (63Ni), which emits β particles, is loaded on the GaN PIN diodes to achieve GB. Current-Voltage (I-V) characteristics shows that the GaN PIN diodes have leakage current of 18 pA at -10V due to consummate fabrication processes, and the open circuit voltage of the GB is estimated about 0.14 V and the short circuit current density is 89.2nAcm-2 . The relative limited performance of the GB is due to thick dead layer and strong backscattering of β particles, Which lead to less energy deposition in GB. However, the conversion efficiency of 1.6% and charge collection efficiency (CCE) of 100% for the GB have been obtained. Therefore, the output power of the GB are expected to greatly increase with thin dead layer and structural surface weakening the backscattering.