The electronic and the electrical properties of the Sr doped CaMnO3 oxide for Ca site are studied by the density funtional theory calculation method. The Sr doped CaMnO3 oxide bulk samples are prepared by the citrate acid sol-gel method as well as the ceramic preparation method, and the thermoelectric transport properties are analyzed. The results show that the Sr doped CaMnO3 oxide still has the indirect band gap yet with the band gap energy slightly decreasing from 0.756 eV to 0.711 eV. The effective mass of carrier near Fermi level is modified and the carrier density near Fermi level is also increased. The ability to release electrons of Sr is stronger than that of the Ca, and the Sr acts as n-type donor doping specy within the CaMnO3 compound. The electrical resistivity values remarkably decrease for the Sr doped CaMnO3 oxide materials. The Seebeck coefficient increases slightly to a certain extent compared with that of the intrinsic CaMnO3. The resistivity values for the Ca1-xSrxMnO3 (x=0.06, 0.12) samples at 373 K decrease to 25% and 21% of the un-doped intrinsic CaMnO3 sample, respectively. The Seebeck coefficients for the Ca1-xSrxMnO3 (x=0.06, 0.12) samples at 373 K increase to as high as 112.9% and 111.1% of the Seebeck coefficient for un-doped intrinsic sample, respectively. The thermoelectric performance is effectively enhanced by Sr doping for the CaMnO3 oxide material.