The invention relates to a full-distributed optical fiber strain and vibration sensor based on coherent heterodyne detection, which comprises a laser (1), a coupler, a pulse modulation module, a programming gain amplifier (4), an optical amplifier, a circulator (6), a sensing fiber (7), a polarization-preserving fiber (8), the coupler, a balancing photoelectric detector (10), a reversal switch, a mixer, a microwave source, a band-pass filter, and a signal processing unit, wherein the continuous light output by the laser (1) is divided into two paths after passing through the coupler (2); an output end of the balancing photoelectric detector is connected to the reversal switch; the reversal switch is switched to a channel 1 and a channel 2; when the channel 1 is switched on, the system utilizes the Brillouin optical fiber time domain reflection to measure; and when the programming gain amplifier (4) is closed and the channel 2 is switched on, the system utilizes the polarization optical time-domain reflection to measure. By using the full-distributed optical fiber strain and vibration sensor provided by the invention, the full-distributed measurement for strain as well as the weak vibration and the full-distributed measurement for vibration can be performed on a single optical fiber.