As one of the typical electrolyte materials for proton conducting solid oxide fuel cells, BaZr_0.1Ce_0.7Y_0.2O_3-δ (BZCY) possesses advantages such as high proton conductivity and stability. However, sintering activity of BZCY electrolyte is poor, usually requiring high sintering temperature for densification, which is inconducive to the preparation and application in cells. This study aimed to reduce the sintering temperature of BZCY electrolyte and explore the influence of sintering additives such as NiO, Fe₂O₃, ZnO, and CuO on the sintering characteristics of BZCY in detail. The results indicate that the oxides except Fe₂O₃ can effectively promote the grain growth of BZCY sintered body. Among them, the addition of CuO has the most significant promoting effect on the sintering process of BZCY. After adding 2% (in mass) CuO into BZCY (BZCY-2%CuO), even if the sintering temperature was reduced to 1250 ℃, the relative density of the sintered body still maintained higher than 98%. Additionally, the conductivity of BZCY-2%CuO was up to 2.7×10^-2 S·cm^-1 at 600 ℃ in wet H₂ atmosphere, which was nearly 5 times higher than that in wet air. More importantly, BZCY-2%CuO electrolyte exhibits negligible electronic conductivity under cell operating conditions while maintaining excellent stability.