Abstract: The microwave properties of the micron absorbent have reached the theoretical limit, for its three dimension constructer and have no further promotion spaces. Meanwhile, too high planar density also limits its applications in more filed, e.g. all kinds of aircraft. The metal film has a two dimension structure with the magnetic moments lying on the plane. And the nano-structure of films also benefits higher microwave permeability. The permeability of magnetic films usually is above 100 at 2GHz, which could give excellent microwave properties with very low thickness and planar density, and the film has a potential to be the excellent microwave absorption material. The metal film usually has the good conductivity, which leads to the high microwave reflection and the bad interfacial microwave match. The complex permittivity of the metal film must been controlled to be suitable for the interfacial microwave match, so that the incident microwave could be easy to penetrate into films and be transformed into heat. Patterned films possess the discontinuous structure and could be regarded as the effective medium composed of metal and air. Low permittivity of metal films could be achieved by this way. The dielectric mechanism of patterned metal films, and how to manipulate it, are discussed in the paper. The calculation work has been conducted based on re-generalized effective medium theory. The results indicate patterned films with cell size in the micron range could suppress the effect of eddy current, and reduce the permittivity of films below 1000. The permittivity of patterned films combined their high permeability would give a perfect interfacial match property for the microwave absorption application. Base the calculation result, a new type film microwave absorption material will be realized. The further preparation process should be tried to tailor the metal film.