Fe partial substitution for Co on B-site may tradeoff stability-activity for BaCoO_3-δ perovskite. However, large radius mismatch between Ba and Co/Fe favors the formation of a low symmetric hexagonal phase BaCo_1-xFe_xO_3-δ, which may experience phase structural transitions with varying temperatures and could induce structural reliability issue of associated devices. The B-site doping with high valence elements may facilitate to form cubic BaCo_1-xFe_xO_3-δ perovskite, it could also significantly deteriorate their catalytic property. The Yb³⁺ with ionic radius being larger than those of Co⁴⁺ and Fe⁴⁺ could be used as B-site dopant to tune Goldschmidt tolerance factor of BaCo_1-xFe_xO_3-δ to 1 and therefore stabilize its cubic structure. Additionally, the electronegativity of Yb is lower than that of Co and Fe. This would induce a slightly lower valance of Co and/or Fe when Yb is used as B-site dopant, facilitating oxygen vacancy generation and electrochemical kinetic process. In this research, Yb-doping effects on crystal structure and performance of BaCo_0.7Fe_0.3-xYb_xO_3-δ (x = 0.05, 0.10 and 0.15) are systematically evaluated. The results indicate that Yb partial substitution for Fe on B-site is able to effectively stabilize crystal structure with highly cubic symmetry and BaCo_0.7Fe_0.2Yb_0.1O_3-δ is among the best as cathode material for intermediate temperature SOFCs.