In this paper, the deflection of the movable crossbeam during the pressurization process of the ultra-large hydraulic press is studied. The electromechanical and hydraulic systems of the ultra-large hydraulic press are analyzed, and a joint AMESim-ADAMS simulation model of the mechanical system, the oil system, and the correction control system are established. The simulation analyzes the deflection control of the working cylinder in the 1600 MN pressurized state, the movable crossbeam in the positive load without deflection correction, positive load with deflection correction, eccentric load with 300 mm of deflection in X-positive direction, and eccentric load with 300 mm of deflection in XZ-positive direction. The results show that the correction control system needs to be turned on synchronously at the beginning of the pressurization; under the pressure of 1600 MN and the maximum eccentricity of 300 mm, the velocity error of the movable crossbeam can be controlled within 7 %, and the parallel control precision can reach 0.14 mm/m.