The main method to improve the resolution of optical system is enlarging the pupil of optical system, and by using several segmented mirrors to get an equivalent large diameter primary mirror is a common way. After the deployment on orbit, there will be deviation between deployment position and the designed position, which is position error. The error determines the imaging quality of the optical system. So the precision of the position of segmented mirror is needed to be analyzed to make sure the error will not destroy the image quality. This paper uses Fizaeu interference technique to detect the piston error between segmented mirrors, and analyses the detect theory of it. Build model in the ZEMAX and simulate the change of stripe's position and brightness information. In the end, we get the same result of MATLAB, which testifies Fizaeu is of feasibility to detect the piston error. © 2019 Elsevier GmbH