Abstract: Prism mechanism is critical part to achieve alignment. To improve the accuracy of alignment, with tilt and deflection of prism base-edge, dynamic optical theory was used to derive the calculation formulas of angle deviation between actual and ideal emergent ray directions of reflected ray as well as the relative position deviation between actual and ideal images. A two-step method to detect and adjust the tilt angle and deflection angle of prism base-edge respectively by using high-precision, high-speed digital micrometers and micro-vision system was proposed. Experiments and error analysis were carried out. The result has verified the validity of aforementioned calculation and adjustment methods.