The double perovskite oxides are widely investigated as cathode materials for solid oxide fuel cell (SOFC) due to their superior ionic electron conductivity. In this work, Pr_0.9Ca_0.1Ba_1–xCa_xCo₂O_5+δ (0≤ x≤ 0.3, PCBC) was prepared by a modified complexing sol–gel process. Based on the electrical conductivity results, Ca ion co-doping can effectively improve the conductivity of the material. The electrochemical performance results indicate that the cathode with x of 0.2 has the optimum oxygen catalytic activity, and the polarization impedance is only 0.069 Ω·cm² at 700 ℃. The oxygen vacancy formation energy, density of states, as well as O s and O p band center of PrBaCo₂O_5+δ, Pr_0.75Ca_0.25BaCo₂O_5+δ, and Pr_0.75Ca_0.25Ba_0.75Ca_0.25Co₂O_5+δ materials were calculated based on the GGA–PBE function. It is indicated that Pr-site doped with Ca can reduce the oxygen vacancy formation energy, while Ba-site doped with Ca can increase the oxygen vacancy formation energy. The calculation results of O p band center show that the strategy of Ba–site doped with Ca can effectively increase the oxygen reduction activity. The co-doping strategy of double perovskite can improve the thermal expansion, conductivity, electrochemical performance, and long-term stability of the material.