To explore the influencing factors of pressure oscillation induced by the movement of entrapped air pockets in pressure pipelines, and to fully characterize the transient effects of air pockets motion, pressurized air pockets in a more complex experimental piping system were studied, which was different from previous experiments based on the discharge of non-pressurized air pockets at the end of a simple piping system. The law of pressure boost caused by the movement of air pockets under different flow and volume conditions was discussed. The experimental results show that the single influencing factor of system flow rate and air pocket volume on pipeline pressure is not linear, but presents a convex parabola relationship. The maximum pressure boost value is determined by the opening of the end valve, the change of water velocity gradient caused by gas discharge, and the buffering effect of the remaining air pockets.