We　present　a　theoretical　study　on　structural　stability,　magnetism　and　ferroelectricity　in　an　A-site　ordered　cubic　perovskite　LaMn3Fe4O12　(　LMFO)　compound　using　first-principle　calculation.　The　calculated　results　indicated　that　LMFO　was　a　thermodynamically　stable　insulator　and　the　stability　of　the　dual　G-type　antiferromagnetic　(AFM)　ordering　was　the　most　stable　state　among　all　considered　spin　configurations.　Besides,　a　magnetically　induced　ferroelectricity　with　the　theoretical　maximum　polarization　of　around　88.63　mu　C/m(2)　along　the　＜　1　1　1　＞　directions　was　approved　and　the　ferroelectricity　was　attributed　to　the　probable　interaction　between　Mn3+　and　Fe3+　ions　with　a　collinear　spin　configuration　in　this　cubic　perovskite　structure.　(C)　2017　Elsevier　B.V.　All　rights　reserved.