Electronic structures and magnetic properties for iron-selenide KFe2Se2 axe studied by first-principles calculations.The ground state is collinear antiferromagnetic with calculated 2.26μB magnetic moment on Fe atoms; and the J1 and J2 coupling strengths are calculated to be 0.038eV and 0.029eV.The states around EF are dominated by the Fe 3d orbitals which hybridize noticeably to the Se 4p orbitals.While the band structure of KFe2Se2 is similar to a heavily electron-doped BaFe2As2 or FeSe system,the Fermi surface of KFe2Se2 is much closer to the FeSe system since the electron sheets around M are symmetric with respect to x-y exchange.These features,as well as the absence of Fermi surface nesting,suggest that the parent KFe2Se2 could be regarded as an electron doped FeSe system with possible local moment magnetism.