Optical fibre sensor has the advantages of small size, light weight, anti-electromagnetic interference, and high measurement accuracy, which has important applications in research and industrial production. To design an optical fibre displacement sensor ( OFBDS ) with simple structure and high measurement accuracy, the unified model of the commonly used OFBDS structures was proposed and the feasibility of the intensity-modulation of multi-structural optical fibre bundles was analysed based on the arrangement characteristics of the fibre bundle end-face. The intensity-modulation characteristic of different fibre bundles was analysed, and the single coil coaxial fibre bundle was chosen as the fibre probe in this study. The sensor hardware system was designed. Lastly, the calibration experiment, temperature interference experiment, changes of measured plane surface area, and the dynamic experiment were conducted. Results showed that the sensor linear measurement range was about 3 mm, and the sensor system had excellent static and dynamic characteristics.