The electrical conductivities of Sr2CoRO6 (R=Mo, Nb) under different oxygen partial pressures and their crystal structures were investigated. Their conducting mechanisms were proposed. X-ray photoelectron spectra revealed that the dominated oxidation state of Co2+ was in Sr2CoMoO6 but Co3+ in Sr2CoNbO6. The crystal lattice structures of Sr2CoRO6 were identified by X-ray diffraction and their parameters were calculated by using Rietveld method. The refined crystal structures of Sr2CoRO6 have been used to construct their own conducting channel model. And the electrical conductivities were measured by using an electrochemical workstation with four-terminals method through controlling the oxygen partial pressure of the testing environment. The results show that the electrical conductivity of Sr2CoMoO6 is 0.36 S·cm−1, much lower than that of Sr2CoNbO6 (7.81 S·cm−1) in air at 973 K, which is assigned to the difference of their conducting channels. And the electrical conductivity of Sr2CoMoO6 increased linearly with the decrease in PO2, reaching 2.05 S·cm−1 when PO2 = 10−21 atm at 973 K, while Sr2CoNbO6 presented an opposite trend. It was supposed that the different valences of cobalt in Sr2CoMoO6 and Sr2CoNbO6 lead to the different electron conducting channels and different changing trends of electrical conductivities with the decrease in oxygen partial pressure.