The transparent electrode characteristics of the SnO2/AgNi/SnO2 (OMO) multilayer structures prepared by sputtering were investigated according to the annealing temperature. Ni-doped Ag of various compositions was selected as the metal layer and heat treatment was performed at 100~300℃ to evaluate the thermal stability of the metals. The manufactured OMO multilayer structures were heat treated for 6 hours at 400~600℃ in an N2 atmosphere. The structural, electrical, and optical properties of the OMO structures before and after annealing were evaluated and analyzed using a UV-VIS spectrophotometer, 4-point probe, XPS, FE-SEM, etc. OMO with Ni-doped Ag shows improved performance due to the reduction of structural defects of Ag during annealing, but OMO structure with pure Ag shows degradation characteristics due to Ag diffusion into the oxide layer during high-temperature annealing. The figure of merit (FOM) of SnO2/Ag/SnO2 was highest at room temperature and gradually decreased as the heat treatment temperature increased. On the other hand, the FOM value of SnO2/AgNi/SnO2 mostly showed its maximum value at high temperature(~550℃). In particular, the FOM value of SnO2/Ag-Ni (3.2 at%)/SnO2 was estimated to be approximately 2.38×10-2 Ω-1. Compared to transparent electrodes made of othe...