Abstract: The microstructure of SWRH72A steel wire under cold-drawn deformation were studied with SEM. The changes in magnetic properties of steel wire with increasing drawing strain were investigated using VSM. The results showed that originally straight pearlite plates become wavy after drawing at cross-section.Highly elongated pearlite colonies develops as a result of their stretching and rotation towards the wire axis. The coercivity and residual magnetization of steel wire increase with increasing drawing strain. The saturation magnetization of steel wire was almost unchanged,2.885 69×104 A·m-1. And it increased to 2.956 33×104 A·m-1 with the strain extending to 2.60.Cementite content of SWRH72A steel wire by calcutation was lowered from 10.8% in undeform to 8.6%.