A wavelength-scanning type Brillouin optical time-domain reflectometer based on Brillouin frequency shift wavelength independence comprises an adjustable wavelength narrow linewidth laser source (01), a coupler (02), a pulse modulation unit (03), a circulator (04), an optical fiber (05), a scrambler (06), a coupler (07), a detector (08), a microwave signal source (09), a mixer (10), a narrowband low pass filter (11) and a signal acquisition processing unit (12). The adjustable wavelength narrow linewidth laser source generates laser, the laser passes the coupler (02) which outputs two beams, one beam is modulated by the pulse modulation unit into detection pulsed light, and the detection pulsed light is injected into the optical fiber to activate spontaneous Brillouin scattering light. The other beam outputted by the coupler (07) serves as local oscillation reference light and is coupled and superposed with the spontaneous Brillouin scattering light through the scrambler by the coupler (07). The coupled and superposed light passes through the detector for photoelectric conversion.