BaBiNb₅O₁₅ (BBN) based oxide-ion conductors have great potential for application in intermediate-temperature solid oxide fuel cells. In this work, electrical property enhancement is achieved by Sr²⁺ ion doping and sintering process improvement. The BaBi_1−xSr_xNb₅O_15−δ samples are prepared by the traditional solid-state reaction to investigate their electrical properties and oxygen relaxation behavior. Upon increasing the Sr²⁺ doping amount, the bulk conductivity of BaBi_1−xSr_xNb₅O_15−δ compounds increases first and then gradually decreases, and the bulk conductivity of the sample is the best when the doping concentration is 2 mol%. With the increase of Sr²⁺ doping, the activation energy shows a first decreasing and then increasing trend. Compared with the traditional sintering method, the total conductivity of the BaBi_0.98Sr_0.02Nb₅O_15−δ sample prepared by the two-step sintering method is greatly improved. These results have great implications for improving the electrical performances of BBN-based oxide conductors and studying their sintering process.