Based on the experimental results and analysis of grain size and content of soft magnetic phase in Nd₂Fe₁₄B/α-Fe permanent magnetic material,simple models were established to give a further evidence and relatively accurate result of grain size and content of soft magnetic phase in two-phase nanometer composite permanent magnetic materials. The comprehensive analysis shows, when obtain the optimal magnetic of Nd₂Fe₁₄B/α-Fe permanent magnetic material, the size of soft magnetic phase ~ 8 nm, and the content ~ 40%. The data lay a foundation in theory for the requirement of grain size and phase content to obtain the optimal magnetic of two-phase nanometer composite permanent magnetic materials, FePt / Fe₃O₄ and Sm₂Fe₁₇N₃/α-Fe for example.