Objective To investigate a special optimized technique for computer aided measure, and provide an anatomical basis for the placement of lag screw in the posterior column of the acetabulum. Methods Eighty accurate hemi-pelvis models were reconstructed from 40 CT data sets. The optimization objective function, for improving the placement of lag screw, was built by adaptively sampling the weighted distance of screws to the acetabulum boundary according to surgical requirements, and the two end points of the screw were modified iteratively to reduce the objective value under constraints. The statistical measure data were provided according to new anatomical reference landmarks for clinical use. Results The optimal entry point for lag screw fixation in the posterior column was located (18.90±1.19) mm above the line connecting the anterior borderline of the sacroiliac joint with the notch between the anterior superior iliac spine and the anterior inferior iliac spine, and the connecting line was divided by the perpendicular project point with a proportion of 2∶3. The mean inclination of the lag screw was (85.99±2.04)° for angle with the line connecting the entry point with the notch between the anterior superior iliac spine and the anterior inferior iliac spine, and (37.54±1.55)° for angle with the line connecting the entry point with the perpendicular project point; the mean length of the lag screws in the posterior column was (133.07±3.22)mm. Conclusion The automatic optimized technique for the computer aided measure is very efficient and has many advantages over the conventional manual dissection methods, and