Aiming at the problems of large load fluctuation and end folding defects caused by irrational design of die structure parameters in the three-directional press bending process of 6082 aluminum alloy U-shaped arm, a process control strategy based on the cooperative optimization of active die structure parameters was proposed. Then, through DEFORM-3D finite element simulation, the influences of active die cavity depth h and tilt angle θ on the load distribution, stress field and forming quality in the pre-bending,bending and flattening stages were systematically analyzed. The results show that the tilt angle of cavity has a greater effect on the maximum load in the pre-bending stage. When the tilt angle of cavity θ≥80.5°, the cavity depth has a greater effect on the maximum load in the bending and flattening stage, and the optimal process parameter combination is h=80 and θ=80.5° , which reduces the total forming load by 18.7%, and the angle of billet is a minimum of 73° after pre-bending. The end folding defect after bending is effectively controlled while the maximum load of equipment is reduced. This study provides a theoretical basis for the structural optimization design of three-directional press bending die and the improvement of the forming quality for aluminum alloy U-shaped arms.