In this paper we report BiFeO 3 -Bi 2 Fe 4 O 9 composite with negative permittivity at about 1 GHz, a necessary step to construct a real metamaterial with both negative permeability and negative permittivity. This purposely designed material is obtained by a self-assembly procedure with the same starting raw material. The composite material shows a dielectric resonance at about 1 GHz. The reason for the resonance is analyzed, based on the equivalent resistance-inductance-capacitance circuit, which is confirmed through the theoretical model. Furthermore, the frequency of the resonance can be easily tuned by varying the composition ratio. Our results show that the composite is applicable in the new field of metamaterials for the miniaturization of antennas.