In the investigation, the fiber Bragg grating-based sensor system is proposed and demonstrated to monitor temperature and strain individually. In order to obtain a stable and accurate sensing signal, an erbium-doped fiber (EDF) ring laser scheme with a 2 m long unpumped EDF as the saturable absorber is also proposed. Hence, the observed stabilization of output power and sensing wavelength can be less than 0.1 dB and 0.02 nm, and 0.3 dB and 0.02 nm in the sensor system, respectively, in the back-to-back state and 25 km fiber link. Hence, this sensor system can improve the output stability of the sensing signal. In addition, the temperature- and strain-induced wavelength shifts can be operated in the range of 20 °C-70 °C and 0-37 500 µϵ, respectively.