Due to the poor chemical stability of CeO2-based materials, doped CeO2 electrolytes are generally used as a stabilized ZrO2 protection layer/doped CeO2 electrolyte bilayer structure. Since the ionic conductivity of stabilized ZrO2 materials is lower than that of doped CeO2 materials, the thickness of the ZrO2 protective layer needs to be optimized. Thus, in this study, nano-porous anodic aluminum oxide template based scandia stabilized zirconia (ScSZ)/gadolinia doped ceria (GDC) bilayer electrolyte low temperature solid oxide fuel cells (LT-SOFCs) are successfully fabricated and investigated. The optimized thickness of the ScSZ protection layer is revealed by physical and electrochemical characterizations to maximize the performance of LT-SOFCs. The 160 nm ScSZ/400 nm GDC bilayer electrolyte LT-SOFC achieves a maximum power density of 252 mW · cm-2 and an open circuit voltage of 1.02 V OCV at 450 °C.