The　electron　spin　transport　in　an　asymmetrical　magnetic　superlattice　(MSL),　which　is　due　to　the　periodic　barriers　with　abnormal　one　in　height,　has　been　theoretically　studied.　The　effects　of　the　abnormal　barrier　in　the　MSL　have　been　introduced　by　a　defined　asymmetry　factor,　which　corresponds　to　the　changeable　height　of　the　abnormal　barrier.　The　results　show　that　in　the　ballistic　transport　region,　the　spin-up　electron　transmission　and　conductance　can　be　dramatically　depressed　by　the　enhancement　of　the　asymmetry　factor.　However,　the　spin-down　transmission　and　conductance　are　only　slightly　affected.　It　means　that　the　spin　transport　in　the　asymmetric　MSL　is　obviously　different　from　that　in　the　symmetric　MSL.　In　addition,　the　value　of　spin　polarization　of　the　conductance　can　be　well　controlled　by　the　asymmetry　factor　in　a　wide　range　of　energy,　and　highly　polarized　transport　is　possible.　Furthermore,　the　number　of　the　abnormal　barriers　can　also　strongly　affect　the　oscillation　of　the　spin　polarization.　(c)　2006　American　Institute　of　Physics.