Enhanced ionic conductivity has been frequently detected in the hetero-structure composites made of dissimilar structures, triggering a series of studies to develop new electrolytes for solid oxide fuel cells (SOFC) based on different structures. To verify whether such kind of enhancement exists in the composite of similar structure, a new composite electrolyte based on perovskite BaZr0.1Ce0.7Y0.1Yb0.1O3-delta (BZCYYb) and BaCo0.4Fe0.4Zr0.1Y0.1O3-delta (BCFZY) is developed and studied in this work. Micro-structural study reveals the BZCYYb and BCFZY particles form sufficient hetero-interface regions in the composite, resulting in an enrichment of oxygen vacancies. Electrical conductivity measurement detects more than two times enhancement of ionic conductivity in the composite as compared to BZCYYb, which is likely due to the strain at the hetero-interface caused by lattice mismatch. The SOFC with the 7BZCYYb-3BCFZY electrolyte exhibits a peak power density of 720 mW cm-2 at 550 degrees C, which is superior to that of the BZCYYb SOFC. Further analysis of impedance spectra and in-situ ionic conduction confirms improved ionic conductivity of the 7BZCYYb-3BCFZY electrolyte in the fuel cell. Our study indicates that the composites based on the same structures (perovskite-perovskite) can also enable enhanced interface ionic conductivity, but the enhancement is not as strong by orders of magnitude as in case of the composite made of highly dissimilar structures.