optical fiber sensing was proposed, and the measurement principle and key technologies of the system were studied. Through modeling and analyzing the intensity of the emitted light of the fiber-optic sensor emitting fiber, the corresponding relationship between the intensity-enhanced function and the measured distance was found. Aiming at the influence of the stability of the light source in the measurement system and the change of the surface reflectivity of the workpiece on the topography measurement, proposed a compensation technique to increase the reference light path. The experimental results show that the calibrated displacement modulation characteristic curve has good repeatability, the repeatability error is 3.82%, and the linear range of the curve slope is 0.2～0.6 mm, and the sensitivity is 1.11 mW/mm, the micro-displacement measurement is performed in the linear interval, and the average absolute error of the measurement is 2.8 μm. The step of the workpiece with a height calibration of 100.0 μm is measured 10 times, and the average absolute error of the step height is 6.2 μm, which indicates that the measurement system can better measure the surface topography of the work piece.