Abstract: Based on our proposed new method of non-contact and non-invasive technique, we have developed a prototype experimental system for measuring three-dimensional position of points of surgical interest. In this paper, the structural model of the system is introduced, a three-dimensional template is designed with several small metal landmarks, and some experimental results are given. Finally the accuracy of location is discussed through analyzing the influence of various factors.This implemented system is successful in principle, and possible in the future application, but it needs to be improved in the precision of locating. From many experiments, we find four major factors affecting the accuracy of the system . They are mechanical interface between the 3D template and the end of PUMA 260 robot, the deformation of the mechanical links caused by the weights of the force sensor and the 3D template mounted on the end of the effector, the errors from medical image distortion and the data uncertainty caused by the selection of the projection points on the images. Among them, the mechanical interface is very important to improve the accuracy of the system, because the transformation matrix created from three landmarks on the 3D template is a key computation for registrating between the target point in medical image and the real symptom point of disease within patient's bady.