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Short-range order has been thought to be the primary reason of the abnormal increase of electrical resistivity after aging treatment in the Ni-20Cr based precision resistance alloys. However, there is no report on the microstructures of this alloy, to say nothing of the lattice type of the short-range order. In this work, the microstructure of a commercial Ni-20Cr-3.2Al-2.5Fe precision resistance alloy was investigated using X-ray diffraction, transmission electron microscopy and atom probe tomography techniques. A random solid solution was initially formed after quenching treatment. Short-range order with the L12-type structure, which was formed due to aging treatment, resulted in a decrease in lattice parameter and an increase in electrical resistivity. The short-range order microdomains distributed in a random matrix coherently with the same composition. Keywords: L12 short-range order, Precision resistance alloy, Microdomain, K-state, Transmission electron microscope