The concept of deformation-enhanced transformation of ferrite in plain low carbon steel is introduced. The characteristics are presented. Systematic works conclude that deformation significantly enhances the ferrite transformation of undercooled austenite in plain low carbon steel. Nucleation is the dominant process of the transformation. Until the completion of the transformation, nucleation is always repeated, especially at the zone in front of the newly formed ferrite grains, which restrict the grain growth and lead to formation of very fine ferrite grains. Three stages of kinetics are clearly shown from the experimental measurement, which correspond to nucleation at grain boundaries, at the zone in front of newly formed ferrite grains and within residual austenite.