Based on the interference principle of conjugated vortex beams， the relationship between the rotation angle and displacement of the interference image was theoretically analyzed， and the feasibility of the theory by optical simulation system was verified. An interferometer composed of a spatial light modulator and an improved Mach-Zehnder interferometer was designed to measure the displacement of the nano-displacement stage using the conjugated vortex beams with different topological charges.The experimental results showed that when the displacement was 100 nm， 200 nm and 250 nm， the relative error was the smallest when the topological charge was 3， which was 2.19 %， 1.28 % and 1.27 %， respectively. The research results were helpful to improve the accuracy of displacement measurement based on conjugated vortex beams interference.