Carbon　dioxide　adsorbed　on　different　kinds　of　CaO　surfaces　has　been　investigated　with　the　help　of　the　first　principle　density　functional　theory　plane　wave　calculations.　Various　possible　configurations　have　been　considered　and　the　calculated　results　showed　that　CO2　was　strongly　adsorbed　by　C　atom　bonded　with　the　CaO　(001)　and　(110)　surfaces　with　adsorption　energies　of　1.38　and　3.22　eV,　respectively.　The　adsorption　of　CO2　molecule　on　defect　surfaces　is　complicated　compared　with　that　on　the　pristine　surfaces.　The　adsorption　energy　of　CO2　absorbed　on　the　CaO(110)　surface　is　larger　than　that　of　CaO(001)　surface　when　the　type　of　defect　surface　is　the　same.