By transferring 100 nm gold-coated CVD monolayer graphene onto the well-polished surface of D-shaped fiber, we achieve a graphene in-line polarizer with a high polarization extinction ratio of ～27 dB and low insertion loss of 5 dB at 1550 nm, meanwhile achieving a strong saturable absorption effect of 14%. The manufacture of thisgraphene in-line polarizer also simplifies the graphene transfer process. To explore the potential applications of the new device, we also demonstrate noise-like pulse generation and supercontinuum spectrum generation. By launching the designed graphene device into a fiber ring laser cavity, 51 nm bandwidth noise-like pulse is obtained. Then, launching the high-power noise-like pulse into high nonlinear fiber, a 1000 nm wide supercontinuum spectrum is obtained, which is favorable for sensing and nonlinearities scientific fields.