The effects of tilt, roll, and heave ship motion on pressure drop were investigated in a laboratory-scale random packing, which was located at a six degree of freedom (6DoF) motion parallel platform. The water-air system was adopted, and various operating condition (liquid load and F-factor) as well as sea states were tested. In tilted states, the pressure drop was decreased as the tilted angle increased, which was associated with the reduction in liquid hold-up. Under a roll and heave motion, it was found that the pressure drop fluctuated around the value of vertical state. Subsequently, the relative change in pressure drop was introduced to reflect the influence of sea state. It was found that the relative change in pressure drop monotonously decreased as the heave motion frequency decreased, but it could inversely increase under a low-frequency roll motion, particularly under high liquid load with a large size Pall ring.