Aiming at the problem of displacement measurement in narrow space with complex structure, a non-contact measurement system of image displacement based on optical fiber is proposed. The measurement principle and system function of the test system are analyzed, and the overall scheme and hardware selection are designed. In order to realize the image displacement calculation, the digital processing processes such as region extraction, image correction, enhancement and binarization are adopted according to the characteristics of the image taken by the fiber optic endoscope. The software interface is developed by C + + language, based on the network platform, and constructed in the form of dialog box, covering the display of various measurement data. Finally, the test system is verified by comparison, centrifugal and vibration tests. The experimental results show that the measurement accuracy of the test system can reach 10 μm, and the system can adapt to the displacement measurement of complex structures in a narrow space in a variety of complex environments.