The invention discloses a high-accuracy distributed optical fiber sensing system based on a narrow linewidth high-order Brillouin Stokes wave. The system comprises an adjustable semiconductor laser (1a), a single-frequency semiconductor laser (1b), a frequency locking device (2), a first polarization controller (3a), a second polarization controller (3b), an acousto-optic modulator (4), a one-wayoptical fiber amplifier (5a), a bidirectional optical fiber amplifier (5b), an optical circulator (6), a multi-wavelength narrow linewidth Brillouin optical fiber laser (7), an adjustable optical filter (8), a photoelectric detector (9) and a data collection card (10), wherein the multi-wavelength narrow linewidth Brillouin optical fiber laser (7) consists of an automatic following multi-wavelength narrow-band filter (7a), a sensing optical fiber (7b), a bidirectional Er-doped optical fiber amplifier (5b) and a Faraday polariscope (7c). The system is reasonable in design, the multi-wavelengthnarrow linewidth Brillouin optical fiber laser is used, and a high-order Brillouin Stokes wave frequency shift amount is detected to realize high-accuracy temperature and strain detection.