Abstract: In order to achieve the precise positioning of the dual cameras of the image measuring instrument to meet the automated measurement requirements of a large number of types of parts in batches. A visual guidance module composed of a large field of view machine is introduced into the existing image measuring instrument. However, it is difficult to make the optical axis of the large field of view camera perpendicular to the measured part due to factors such as manual installation. This paper uses a large field of view camera for calibration. Mark points of the board are used for feature extraction, and then the tilt angle between the measured object and the platform is changed. The mathematical function relationship between the tilt angle of the optical axis and the pixel equivalent is established using image processing software and mathematical models, and the correction of the optical axis perpendicularity is achieved The X and Y axis angle allowable ranges are 2.08° and 2.07°, respectively. The experimental results show the effectiveness of the proposed method and reduce the technical requirements for manual installation. The minimum distance of component assembly density is optimized from 0.4 mm to 0.2 mm, which improves the measurement accuracy of components.