Traditional manufacturing processes of 3D force platform (three-dimensional force platform) are purchasing of three dimensional force sensor, calibrating of sensor in specialized agencies and building up with platform table and base. However, due to processing accuracy and installation error, the method of calibration before building up cannot guarantee the global accuracy of 3D force platform, and it is difficult to meet the requirements in practice. An improved method is proposed in this article that calibrating force sensors first, then dynamic monitoring the installation process, and global calibrating the 3D platform, verifying the calibration results at last. This article design a global calibrating system based on the global calibrating method which achieve the function of data extraction, classification, data evaluation and parameter optimization. The 3D force platform is calibrated again using the optimized parameters, and the result shows that the optimized calibration results are in coincide with the calculated results. At the same time, the method of sensitivity optimization based on global calibrating avoids the low efficiency caused by trial-and-error method and repeatedly loaded, and then improves the calibration efficiency and accuracy.