Abstract: The synthetical soft magnetic properties are reported for the newly developed nanocrystalline Fe_73.5Cu₁Nb₂V₁Si_13.5B₉ alloy. The levels of high frequency core losses of the new alloy are P₃/100k =510kW· m^-3, P₂/200k =748kW·m^-3, P₂/500k =3671kW· m^-3 and P_0.5/1000k =871kW·m^-3. They are lower than those of the early developed nanocrystalline Fe-Cu-Nb-Si-B alloys and significantly lower than those of the superior power Mn-Zn ferrite H_7c4. The dependences of core loss on frequency and amplitude flux density have been analysed. The practical applications of the new alloy to several aspects are also reported.