Abstract: Ohmic contact is evaluated under the high-current density, the traditional Transmission Line Method (TLM) structure is innovated, which only age the contacts areas not others. The new method can ensure the reliability and validity when the structure is applied high-current density. According to two times or more SiO2 deposition, it reduces effectively the probability of leading wire fracture. The results show after high-current density: the contact resistivity is rapidly failure early period and degenerates dramatically with time and current density. From the spectrum, AI is a kind of low electromigration resistance metal, the good ohmic contacts are destroyed due to electromigration and the AI is moved off the contact layers. The experiment proved that it is a perfect method after improving to measure the ohmic contact under the highcurrent density.