To measure the high-precision micro-displacement of objects, this paper proposes a measurement technique based on vortex light interference. By improving the traditional Mach–Zehnder interferometric system, a spatial light modulator is used to generate vortex light as a reference light source, which interferes with the spherical object light acting on the object to be measured and produces spiral interference fringes. Small displacements of the object cause the interference fringes to rotate, and the amount of displacement can be determined by measuring the angle of rotation. This technique combines the advantages of laser interference with image processing, a four-step phase-shifting method, and a unwrapping algorithm to generate unwrapped phase maps and displacement-distribution maps, allowing accurate analysis of the micro-displacement of the object. The experimental results show that the measurement error of this method is less than 3%, and the average error of the repeated measurements is 1.4%. The system is not only easy to operate, with high testing accuracy, but also stable and reliable, making it suitable for industries such as precision machining and chip manufacturing, providing an effective solution for high-precision displacement measurement.