The invention discloses a distributed optical fiber sound sensing device and method based on dual-polarization double-sideband modulation. The distributed optical fiber sound sensing device comprisesa narrow linewidth laser source (1), a polarization-maintaining optical fiber isolator (2), a dual-polarization four-parallel Mach-zehnder electro-optic modulator (3), an arbitrary waveform generator(4) for drive in an X polarization direction, an arbitrary waveform generator (5) for drive in a Y polarization direction, an electro-optic modulator bias control panel (6), a 1*2 polarization-maintaining optical fiber coupler (7), an optical fiber polarization beam splitter (8), a first erbium-doped optical fiber amplifier (9), a first optical fiber (10), an optical fiber circulator (11), a second erbium-doped optical fiber amplifier (13), a second optical fiber (14), a four-way output-type 90-degree light mixer (15), a balance photoelectric detector (16), a data acquisition card (17) and a processing unit (18). The distributed optical fiber sound sensing device integrates the advantages of time-domain reflection and frequency-domain reflection, is free from electromagnetic interference,is electrically passive and can achieve distributed sound sensing with a large dynamic range and high spatial resolution.