This article introduces a measurement of absolute distances and displacements by an interferometric technique using a white-light fiber optic spectrometer.Employing a dispersive Michelson interferometer and a low-resolution spectrometer and with different amounts of dispersion in the interferometer,and knowing dispersion in the interferometer and the bandpass of the spectrometer,the absolute distance can be measured.The new technique extends the use of white-light spectral interferometer for distance and displacement measurement with high resolution,and at the same time it do not need the phase-recurring technique.It offers some reference for the measurement of absolute distance.