We present a novel method to fabricate uniform GaN nanocone arrays (GNA) using Nickel-nanoisland masks. The nanoscale conelike arrays with high density can be formed over the entire 2-inch wafer by inductively couple plasma etching. The results of X-ray diffraction exhibit significant decrease on the (102) reflection in GaN sample with the GNA. Field-emission measurements show that the GNA with sharp tips have a turn-on field of ~ 5.5 V/μm. It is believed that the high aspect ratio resulting from the conelike morphology is responsible for the enhancement of the field-emission properties of GNA.