A novel fiber Bragg grating (FBG) sensor system based on virtual instrument (VI) and tunable laser technology is proposed. The fiber wavelength sweep is made for Bragg grating sensor array by the tunable laser source and thus the quasi-static monitoring for multiple FBG sensors is realized. The system also combines dither technique and a feedback loop arrangement, produces a zero crossing at each of the FBG central wavelength and provides improved resolution in determining the Bragg wavelength shifts. The system can also operate in dynamic tracking mode to realize the dynamic demodulation of a single sensor. The data acquisition device introduces the VI technique and simultaneous multiple-channel input and output make the system perform the function of real-time monitoring. Four-element FBG sensors are adopted in the experiment and demodulation resolutions of less than 1 με and 3.3 nε/Hz at 10 Hz for static scanning mode and dynamic tracking mode respectively, are demonstated.