The thin-film polarizer possesses some merits that the crystal one has not, but the former is only suitable to a narrower wavelength range. In this paper the design and fabrication of the flat-type thin-film polarizer for communications of optical fiber are described. The polarizer what we fabricated has rather wide polarized wavelength region, rather high degree of polarization and good environmental stability. The isolation ratio is reached 30 db, and has less loss. The smallest external dimensions of the polarizer is 4 X 4 X 6 mm3.