The experiments of hot extrusion, hard drawing and annealing treatment were carried out in this paper in order to study the effects of these processes to the mechanical properties and structure of MB5B wrought magnesium alloy. The experimental results showed that, the eutectic phase was to melt into magnesium matrix greatly during the heating process and precipitated from matrix with point-like state in transverse section after extrusion. The tensile strength and elongation of billets after above mentioned treatment were equal to those after homogenization treatment. The as-received billets are then drawn continuously under the circumstance that the percent reduction in area(ψ) of each pass was no more than 15% and the total reduction in area was no more than 50%. As the results the tensile strength increased and elongation decreased sharply at the same time. The grains and eutectic phase of alloy after drawing were prolonged significantly. The subsequent heat treatment had little effects on the properties of the hard drawn bar.