A phase sensitive optical time domain reflectometer (OTDR) technology based on the digital coherent detection and Wiener filter is proposed and analyzed, in which the phase and amplitude of the Rayleigh scatting light along the fiber link can be demodulated in real time. Using the proposed method, the vibration position, frequency and intensity for a sinusoidal disturbance signal driven by a lead zirconate titanate (PZT) on a 3.5 km single mode fiber link are obtained exactly. Wiener filter is used to reduce the laser phase noise and additive noise caused the phase fluctuation. A spatial resolution of 5 m for the system is realized.