Abstract: The temperature characteristics of A1GaN/GaN heterosturture's Schottky contact is described by I-V measurement. At room temperature, Schottky barrier height is 0.75 eV, the ideality factor is 2.06. When the temperature rises, Schottky barrier height rises too, but the ideality factor decreases. The main reason is the effect of heterostructure and two dimension electronics gas(2DEG). When the forward current is 1 mA, the forward voltage at room temperature is 1.65 V. The temperature coefficent of the forward voltage between room temperature and 300 ℃ is - 1.6 mV/℃.