Abstract: In order to overcome the limited bandwidth and the weak power of the laser and enlarge the range of the multi-point detection effectively,a tunable fiber laser is designed and used as the source of optical sensor system with WDM and TDM technique.Based on the mode couple theory,using a stepper motor to tune the wavelength of FBG to scan the fiber laser demodulation is analyzed theoretically and studied experimentally.Strain resolution of about 2.9με/step is obtained.The system has high signal-to-noise ratio and can multiplex a large number of FBGs,which is economical and practical in sensor array system.