Like many other semiconductor devices, the ohm contact technology between HgCdTe and a metal electrode is a key part in infrared focal plane array (IRFPA) technology, on which loophole p-n junctions are detectors. In the study of HgCdTe loophole p-n junction, we found that the larger the p-n junction, the larger the leakage current. Therefore, a new etching electrode processing method was proposed. By this method, the detector and electrode can be formed at the same time, and the technical process can be simplified compared with the chemical corrosion electrode method. But an abnormal character of the detector was found during testing. Thus, the electrode, which is twenty times larger than the detector, was designed, and the technical electrode also takes the etching processing. We found that the abnormal character disappears, and the new method was testified as feasible. The ohm contact between p-HgCdTe and a metal electrode was realized.