Abstract: The Ni-doped Ca3Co4O9+δ based ceramics were prepared by the combination of sol-gel and hot pressing method and the effects of Ni-doping amounts on the microstructures and electric transport properties of the ceramics were studied. The results show that with the increase of Ni-doping amount, the grains of the Ca3Co4O9+δ based ceramics were refined and the texture content and degree of orientation decreased. The grain boundary scattering of the ceramic was enhanced due to the doping of Ni, resulting in the increase of the resistivity and the Seebeck coefficient. However, the power factor was decreased, indicating that Ni-doping lowered the electric transport properties of Ca3Co4O9+δ based ceramics.