The interferometric type of optical fiber sensor is an important class of high precision sensors. The multiplexing technique of optical fiber sensor is also an important developing direction of optical fiber sensor. In this paper, the multiplexing optical fiber displacement sensor based on the principles of frequency-modulation continuous wave (FMCW) and heterodyne interference is presented. Since using the frequency modulation of single-longitudinal mode laser diode, the FMCW heterodyne interference system of optical fiber can be easily realized. The basic sensing subsystems are comprised of a Fizeau type interferometer, so the noncontact displacement sensing system has very good reliability. In this paper, a new multiplex method, a four-channel (or 2 X N-channel) multiplexing optical fiber displacement sensors using the scheme of frequency-intensity-division multiplexing is put forward and studied. Many points or multi-dimension displacements or many physical measurands can be measured at the same time. The measurement accuracy of each channel is smaller than 0.1 micrometers , the highest resolution of displacement is 0.01 micrometers . In this paper, also, the influences of the feedback light, the temperature drift on laser diode, the light intensity and cross-talk between the channels for the measurement accuracy are discussed.