Abstract: During the manufacturing process and service, plastic deformation may occur in mechanical structures. In this paper, the correlations between the plastic deformation and Nondestructive Evaluation(NDE) signals of Magnetic Barkhausen Noise(MBN) and Magnetic Incremental Permeability(MIP) methods are investigated via experiments for typical carbon steel. From experimental results, it is found that: the MBN energy signal has an explicit correlation with the plastic strain at a relatively lower-strain range; both the peaks and the initial incremental permeability profile depend on the levels of plastic strains. The measurement results for different carbon steels reveal that the MBN and incremental permeability methods are applicable to quantitatively evaluate plastic deformation in carbon steels.