The growth mechanism of ECCS was investigated by means of metallurgical microscope, SEM and XPS. The results show that the different modes of annealing and rolling have a remarkably effects on the surface morphology and grain size of TFS products. Compact surface Cr-coating of BA material with low porosity the grains are larger and coarser in comparison with that of CA material, while the evident microcracks are found in the surface Cr-coating of DR material. The chemical compositions of ECCS oxide film on steel mainly consist of CrOOH or Cr(OH)3 as the main composition, plus Cr2O3 in definite proportion and a small amount of H2O. Cr(OH)3 is mainly formed from cathodic films generated in the electroplating process. CrOOH as the intermediate resultant was formed in process of Cr(OH)3 loss water to generate Cr2O3.