This invention discloses a whole optical fiber displacement interferometer, which comprises the fiber laser, fiber isolated element, transformation ratio hank decomposer, geometric proportion decomposer, pattern transducer, adjustable fiber attenuating device, fiber amplifier, fiber filter, fiber coupler and photoelectric transducer. This device uses the flange tray to socket or weld, the laser is sent in the fiber. And it supervises the sample changed process followed with the time through the optics probe of the periphery device illumes the probed sample interface and rebounds the information light and the laser of the device beat-frequency intervenes. This invention can test in the some wider range, it can be used to identify the movement direction of the tested; and the structure is compact, and the signal-to-noise ratio is high.