In this paper, the multiplexing technique of optical fiber displacement sensor based on the principles of frequency-modulation continuous wave and heterodyne interference and frequency-division multiplexing is studied. A four-channel multiplexing optical fiber displanment sensors using the scheme of frequency-ampitude-division multiplexing is designed and fabricated. Many points or multi-dimension displacements or many physical parameters can be measured at the same time. The measurement accuracy of each channel is 0.1 μm and the measurement range is more than 1 mm. The hightest resolution of displacement is 0.01 μm.