Abstract: Bolts play a role of fixation in engineering structure, and their working state is directly related to the working state of equipment and even the life safety of personnel. However, most bolts in the real open environment are difficult to be checked. To meet the requirements of bolt automatic maintenance equipment for safe maintenance of bolts in the open environment, more accurate and rapid identification and positioning, to ensure its normal function, and improve the rate of equipment automation, a set of bolt position and attitude measurement method in the open environment was proposed. In this paper, an independent binocular system was built to collect images of hexagon bolts in the real environment after the calibration of camera parameters. The consistency detection of the two images was carried out by NCC method. Feature point matching and three-dimensional calculation were completed to accurately obtain the depth information of the target bolts. At the same time, a 3D CAD model was generated into 2D model database by using virtual camera technology. The bolt and 2D model database in the open environment were searched and matched by Gaussian Pyramid hierarchical method and greedy algorithm, and the optimal matching results were obtained. Finally, the attitude information of bolts in the open environment was measured. The experimental results show that the method is accurate, practical and effective.