According to the research of the mesoscopic structure of Fe73.5Cu 1Nb 3Si135B9 by AFM, we propose a model for n anostructured soft magnetic properties; and explain the influence of the frequency on the magnetic properti es successfully using the model. The model possesses the characteristic of Herze r's or Ji Song's model, and supplement their deficiency. We also study the influ ence of the conductivity σ and the permeability μ on the magnetic properties o f Fe73.5Cu1Nb3Si135B9 for the first time.