Bianisotropic split ring resonator (SRR) metamaterials under TEM waves are analyzed,which reveal that imaginary wave number leads to the SRR resonance.The field distribution over SRRs is expanded into Floquet modes.The metamaterial resonance is engendered by the evanescent modes.The resonance behavior happens in the transmitted modes with the same polarization as the wave incident in the main plane.And the electric and the magnetic resonances are varied with different incidence angle.