First　principle　calculations　are　employed　to　investigate　the　anti-ferromagnetic　CaMnO3　with　regard　to　its　geometry,　ground　state　electronic　structure　and　charge　distributions.　The　G-type　anti-ferromagnetic　CaMnO3　is　found　to　be　more　stable　via　total　energy　minimization　calculations;　the　calculated　energy　band　structure　reveals　its　band　gap　of　0.7　eV.　There　are　combinations　of　light　carriers　in　conduction　bands　and　heavy　carriers　in　valence　bands　that　should　favor　high　thermoelectric　properties.　The　Mnd　and　Op　orbitals　are　responsible　for　energy　bands　near　Fermi　level　and　they　contribute　to　electronic　property.　There　is　strong　hybridization　between　Mnd　and　Op　orbitals　and,　the　hybridization　between　Mn　and　O1　orbitals　is　stronger,　it　is　indicated　that　the　charge　carriers　are　apt　to　transport　along　Mn-O1.　(C)　2010　Elsevier　B.V.　All　rights　reserved.