Development of high coercivity Dy-free Nd-Fe-B permanent magnet, which is the final aim of current project, needs to be carried out by microstructure design and modification. Microstructure design can be done by combination of multi-scale microstructure analysis and large scale micromagnetic simulations. The multi-scale microstructure characterization is currently carried out in NIMS. Large scale micromagnetic simulations will be introduced into the project in collaboration with Danube University Krems. This combination is very important to understand the relation between the microstructure and the magnetic properties.