Abstract: Study the high temperature characteristics of the ohmic contact of Ti/Al/Ni/Au(15 nm/220 nm/40 nm/50 nm) multiplayer contacts to n-type GaN(N_d=3.7×10¹⁷cm^-3,N_d=3.0×10¹⁸cm^-3),the experi- ment shows that the contact resistivity keeps unchanged and shows good temperature reliability when the stor- age temperature under 300℃during the storage time of 0~24 hours;but the ohmic contact has shown evi- dent degeneration after the storage at 300℃for 24 hours and at 500℃for 24 hours respectively.Further- more,the contact resisivity shows unrecoverable characteristic.The contact resistivity will increase with the measurement temperature,and the tendency of increasing is related to doping concentration,The higher the doping concentration,the slower of decreasing the contact resistivity with measurement temperature.Ti/Al/ Ni/Au ohmic contact to heavy doping n-GaN better high temperature reliability.