Aiming at the inaccurate parallel-alignment of two display screens in three-dimensional (3D) measuring system of specular surfaces, this paper proposes a method for generating deformed fringes by software to be equivalent to the exact parallel-alignment of two display screens. The machine vision technology was employed to calibrate external parameters of the two displays, based on which the deformed fringes equivalent to parallel-alignment two display screens were produced by software programming. A camera captured the parallel-alignment fringe pattern through the beam splitter in the camera coordinate system. The difference of the corresponding phase was calculated with the deformed fringe patterns on the two display screens. The proposed method was quantitatively evaluated by the errors of root-mean-square. Experimental results show that the proposed method can reduce the errors of root-mean-square to 24.21% in horizontal direction and 8.15% in vertical direction of the original ones respectively, thus improving the accuracy of 3D measurement system.