The invention discloses a high-performance dynamic distributed optical fiber sensor based on Brillouin and Rayleigh double mechanisms, relates to a high-performance dynamic distributed optical fiber strain sensing technology based on the Brillouin and Rayleigh double mechanisms, and aims to solve the problems that the measurement precision is influenced because accumulated errors of a Rayleigh scattering-based system are increased continuously in a demodulation process, and a Brillouin scattering-based system is low in strain resolution. One path of light is modulated into optical frequency-agile signal light of upper and lower sidebands of a pulse through an electrooptical modulator, the upper sideband is filtered out through a first filter, then the optical frequency-agile signal light is amplified by an erbium-doped optical fiber amplifier to serve as pump light, and the pump light is input from one end of a to-be-tested optical fiber; the other path of light is input from the otherend of the to-be-tested optical fiber; and stimulated Brillouin scattering and Rayleigh scattering occur in the to-be-tested optical fiber, Brillouin scattering signals and Rayleigh scattering signals are separated through a second filter, two detectors detect the Brillouin scattering signals and the Rayleigh scattering signals respectively, and an acquisition module acquires output signals of the detectors. The distributed optical fiber sensor is suitable for distributed optical fiber strain sensing.