In order to realize 3D shape acquisition for large free surface, a data registration method using optical location tracking technology was proposed. A planar target was fixed on the measurement system as the intermediate, the coordinates of some feature points provided by the target in the measurement coordinate system were obtained by a intermediary coordinate transformation method. A location tracking system was constituted by binocular stereo vision, then,the tracking coordinate frame was used as the global coordinate frame to obtain 3D global coordinate of feature points on planar target to derive the transformation matrix from the measurement coordinate frame to the global coordinate frame. All the 3D data of sub-areas obtained by the measurement sensor were unified in the global coordinate frame, and the global measurement for a large object was accomplished. The registration experiment was conducted using 100 feature points on the planar target, and the results show that the single measurement precision is 0.11 mm, and the RMS error of 3D data registration is less than 0.34 mm. The presented method is simple and flexible, and can satisfy the precision requirements.