A GaN-based pin neutron detector with a 6LiF conversion layer was fabricated,and can be used to detect thermal neutrons.Measurement of the electrical characteristic of the GaN-based pin neutron detector showed that the reverse leakage current of the neutron detector was reduced significantly after deposition of a 6LiF conversion layer on the detector surface.The thermal neutrons used in this experiment were obtained from an 241Am-Be fast neutron source after being moderated by 100-mm-thick high-density polyethylene.The experimental results show that the detector with 16.9-μm thick 6LiF achieved a maximum neutron detection efficiency of 1.9% at a reverse bias of 0 V,which is less than the theoretical detection efficiency of 4.1% calculated for our GaN neutron detectors.