Proton-conducting oxides show high proton conductivity operating below 600 °C, which offers a significant advantage in developing low cost and durable solid oxide cells (SOCs) at intermediate-to-low temperature. The ABO3 perovskites based on Ba, Ce, Zr, Y, and Yb are state-of-the-art proton conductors such as BaZr1-xYxO3-δ (BZY), BaCe0.7-xZrxY0.2O3-δ (BCZY), and BaCe0.7-xZrxY0.1Yb0.1O3-δ (BCZYYb). However, it is very difficult for these materials to balance the sinterability, conductivity and stability. To achieve dense electrolyte with high conductivity and long-term stability at the low sintering temperature, one of the most common approach is adding sintering aids in the fabrication processing of proton-conducting oxides. In recent researches, the effect of sintering additives on the electrical conductivity of proton conductors are still in the arguments. This review provides a comprehensive discussion of recent research developments on sintering additives modified proton conducting oxide. Moreover, we summary in detail the influence of different sintering additives on the relative density, grain growth, sintering behavior, and bulk and boundary conductivity of proton conducting oxides, as well as pointing out the potential research directions.