The invention provides a device and a method for significantly increasing an OFDR single scan demodulation speed. The device comprises a swept source, a 1*N fiber beam splitter, an auxiliary trigger module, an auxiliary clock module, a measurement module, a data acquisition card, and a computer. The device can generate three beat frequency signals. In the scanning process of the swept source, under the trigger of the first beat frequency signal, the second beat frequency signal undergoes interference and serves as a clock signal, and the third beat frequency signal is subjected to equal-frequency-interval segmented acquisition. The device and the method realize the N-segment acquisition in the single scan process, can compress the scanning time with the highest proportion in the demodulation speed by N times, and ensure that the data acquired in a segmented manner has strict repeatability in wavelength (frequency). Therefore, the device and the method adopt the idea of segmented acquisition under the premise of ensuring that the OFDR technology realizes communication or remote sensing measurement, compress the scanning time with the highest proportion in the demodulation speed by Ntimes, and significantly increase the OFDR single scan demodulation speed.