Abstract: A reliable low-resitance ohmic contact to n-type GaN was studied. First, a Ti（30nm）/Al（500nm） bilayer was deposited on the Si-doped GaN（3×10¹⁸cm^-3） by evaporation and then annealed in nitrogen at 530℃ for 3 min. After annealing, another bilayer of Ti（100nm）/Au（1000nm） was deposited on the top of Al layer to protect it from being oxidized. This contact show good ohmic contact with a specific resistance of 8.8×10^-5 Ω·cm².The surface of the contact is found to be very smooth, stable and suitable for bonding. The results indicate that the contact can be used for fabrication of high-performance GaN devices.