During final annealing of the grain-oriented 3%Si steel sheet, the secondary nuclei form in the subsurface layer of the sheet, but their growth modes depend on cold-rolling reduction. According to the growth characters of conventional and high permeability grain-oriented silicon steels, a quantitative relationship among the parameters, such as the diameter of primary grains, inclusion factor and critical size of secondary nuclei, is derived by the energy analysis. The calculated result is consistent with experimental data of previous works.