In this paper, with regard to fiducial mark (FM) images produced by a precision fiducial system, we conduct analyses of fiducial mark & unfiducial mark (UFM) detection and positioning. First of all, we select the fiducial marks in an image as a reference fiducial mark (RFM). Then we capture the features on RFM. Finally, we search for FM in the target images based on RFM and locate the coordinates of FM in the images. In this paper, we use FM or UFM in images as the main fiducial target of the automatic precision fiducial system. The purpose of the study is to improve fiducial precision and efficiency. For images with FMs, this paper proposes automatic candidate fiducial mark detection to obtain the RFMs. The searching methods of FMs mainly involve the four fiducial mark image detection often encountered in the industry; namely, traditional fiducial mark search, shelter cross mark detection, different mark color detection and rotational cross mark detection. In order to speed up the search speed, the searching methods combine rough search and fine search. NFM images do not have apparent and readily available marks. It is necessary to decide the RFM. The methods of searching and positioning in images include concentric fiducial mark search, line intersection mark detection, real-time imaging line detection, and mark edge detection. Regarding the experiments in this study, other than automatic candidate fiducial mark detection, in order to verify the accuracy and performance of the positioning method proposed in this paper, we also compare the positioning differences of experimental results in images with FMs and UFMs to the results of Cognex VisionPro. The experiments show that the proposed method can efficiently and accurately locate positions in images.