Abstract: In order to control the polarization states and increase the extinction ratio of the TE and TM output beam,a novel tunable polarization controller was proposed and demonstrated by introducing birefringent material into the coupling prism and polymer acted as the guiding layer of symmetrical metal cladding waveguide(SMCW).In this structure,the guide mode resonance can not simultaneously be excited by TE and TM polarizations at the same incident angle.The incident laser beam energy of the polarization which excites guide mode resonance is coupled into the SMCW,while that of the polarization which dose not excite guide mode resonance is almost reflected.As a result,the TE and TM polarization beams can be separated.Moreover,the polarization selector can be tuned assisted by changing the resonance condition of the guiding mode via applying direct-current voltage on the guiding-layer.The research indicates the inset loss is smaller than 0.2dB and the driving voltage is up to 19V and the extinction ratio is larger than 27dB due to the twice attenuation totally reflected technique.This method is valuable in many potential applications,such as optical information processing,optical routing,optical switch and image processing.