Terahertz pulse reflectometry was employed to characterize the individual layers on metallic substrates. The autoregressive spectral extrapolation based on the modified covariance method was applied to enhance the axial resolution. All coating layers were resolved successfully and the calculated thickness of each layer based on deconvolved results shows a good agreement with the thickness value measured by eddy current technique, highlighting the promising application of terahertz technique on quality control among steel industries.