The invention discloses a distributed optic fiber vibrating sensor which consists of a light source, a first coupler, an acoustic optic modulator, an Erbium-doped optic fiber amplifier, an optic filter, a three-port circulator, a first photoelectric detector, a second coupler, a second photoelectric detector, a high-pass filter, a frequency mixer, a function generator, a low-pass filter, a data acquisition card, a computer and a long-distance sensing optic fiber. The distributed optic fiber vibrating sensor has the beneficial technological effects of detecting the vibrating positions and the vibrating frequencies at the same time and having relatively high resolution ratio for signals.