An erbium-doped fiber ring laser operating at the C-band is experimentally demonstrated. A maximum output laser power of 0.13 dBm with a step-like spectrum and 3-dB bandwidth of more than 0.4 nm is obtained. Output power is theoretically simulated and fits well with experiment data. A slight improvement in signal-to-noise ratio is observed when the ring laser is applied in an optical fiber sensing system compared to a conventional superluminescent laser, and its compatibility with dense wavelength division multiplexing (DWDM) is verified. We believe the ring laser in this article has potential in the future use of a DWDM optical fiber sensing system.