The　lattice　parameters,　electronic　structure,　magnetism　and　multiferroicity　of　compound　BiMn3Fe4O12　were　investigated　by　using　the　first-principle　calculations.　The　total　energy　calculations　indicated　that　BiMn3Fe4O12　was　a　G-type　antiferromagnetic　insulator.　The　ferroelectricity　was　induced　by　magnetism　and　originated　from　the　hybridization　between　Fe　and　Mn　ions.　The　electric　polarization　was　predicted　to　be　around　39　mu　C/m(2)　along　＜　111　＞　orientation.　It　was　sensitive　to　the　lattice　distortion　such　as　Fe　ion　shift　of　FeO6　octahedron　and　a　great　improvement　in　electric　polarization　could　be　possibly　achieved　by　strain　engineering　or　inducing　chemical　pressure.　Furthermore,　the　effects　of　on-site　Coulomb　repulsion　on　electronic　structure,　magnetism,　and　ferroelectricity　were　also　discussed.　It　was　showed　that　with　increasing　U　the　spin　splitting　increased,　resulting　in　an　increased　ban-gap　and　hybridization　between　Fe　and　Mn　ions,　and　then　electric　polarization.　(C)　2017　Elsevier　B.V.　All　rights　reserved.