A 45°tilted fiber Bragg grating (TFBG) is fabricated in photosensitive fiber successfully using the scanning phase mask technique and a Ar-ion laser source. In order to increase the TFBG’s length and its polarization-dependent loss (PDL) effect, a concatenating technique is used in the fabricating process, keeping the uniform structure of the whole grating. The PDL characteristic of the TFBG is experimentally researched in the paper. Using a 45°TFBG as the polarization element, a single-polarized Er-doped fiber laser is demonstrated The polarization-extinction ratio of the output laser is about 30 dB, indicating the high PDL of the 45°TFBG. 45°TFBGs have the advantages of in-fiber, compact, good polarization capability and low price used as polarization devices.