A flat-top multi-channel polarization filter,which can transmit both TM and TE polarized lights,is designed based on the centrosymmetric structure containing an anisotropic medium.The paper analyzes the incident angle and the structural parameters.Then a detailed design example of a 100 GHz channel-spacing filter with excellent properties is given.The cutoff degrees of transmission spectra of TM-polarized light and TE-polarized light are 35.74 dB and 33.40 dB respectively.The FWHMs of them are 17.70 GHz and 19.14 GHz respectively.The transmittances of TM-polarized and TE-polarized lights are both higher than 99.999%.Their center frequencies of transmittance windows accord with the ITU-T standard.In addition,this design structure is also simulated by TFCalc.The simulation result is almost the same as that obtained by the transfer matrix method,which proves the feasibility of the design structure.At last,the influence of the dielectric layers′ refractive indices on performance parameters is studied.The proposed structure is simple and its good polarization filtering characteristics can be obtained with fewer thin film layers.