The pre-pressing machine of the ultra-high pressure ball press adopts the direct connection structure of the hard-tooth reducer motor. Compared with the traditional open-belt drive, it is more stable and reliable, and is more compact and sealed, so as to avoid the on-site dust entering the transmission system and affecting the service life of the motor. The machine adopts a direct-connected hard-toothed reducer, which is connected to the structure of the conventional ball-pressing machine through a pulley or a coupling and a worm reducer. The power transmission efficiency and the transmission accuracy are greatly improved, and the electronic control system is greatly improved. The feedback on the preload motor is more direct and accurate.