The FeCoAlON thin films were prepared by magnetron sputtering. Effect of element addition of Al, O, and N on magnetic materials was studied. Experiment demonstrated that with increasing Al, O and N, the film structure changed from polycrystalline to amorphous, and the films showed soft magnetism. When N content in the film is high, the films show stripe domain structure. The condition and mechanism for the occurrence of stripe domain structure were discussed in detail, and we found that the frequency response of permeability of the films show characteristics of multi-peak resonance.