An optical-fiber low-coherence interferometric sensing system, which is suitable for distance and absolute measurement, is presented. The system includes two optical fiber inteferometers. One of the optical fiber interferometer is embedded in the measured field for sensing the measurand and absolute measurement can be realized. The measurement range is never limited by the optical wavelength. And the other optical fiber interferometer is for demodulating the measurand. Based on wavelength-division-multiplexing technology, the demodulating optical fiber interferometer works in both modes of low-coherence interferometry and high-coherence interferometry. The signal of low-coherence interferometry is for determining the amplitude of the measurand, and the signal of high-coherence interferometry is for measuring the measurand precisely. The measurement range is 6 mm and the resolution is less than 1 nm. The linear correlation coefficient of the displacement measurement is 0.99.