The presence of air bubbles in oil-paper insulation structure can cause distortion of the surrounding electric field and cause partial discharge. In order to clarify the motion characteristics of bubbles in transformer oil, based on finite element simulation methods, the motion trajectory and vertical direction velocity change of bubbles under different electric field intensities are studied. The results show that the extremely inhomogeneous electric field has a push-off and tensile effect on the bubbles, and the distance of the bubbles shift in the horizontal direction increases with the increase of the electric field strength, the movement speed of the bubbles rises first rapidly and then slowly oscillates and decays, and the oscillation frequency decreases at the end of the floating stage, and the speed of the bubbles decreases with the increase of the electric field strength when they are near the needle electrode, but the speed of the entire floating motion increases. A platform for observing the motion of bubbles in the oil-paper insulation structure under the extremely inhomogeneous electric field is built, and the trajectories of the bubbles in different electric fields are recorded, the observations are basically consistent with the simulation. However, with the continuous improvement of the electric field strength, clusters of bubbles are easy to form under the needle electrode, which seriously affects the insulation. The results of the study can effectively assess the operating state of power equipment, which is of great significance for further construction of the digital twin of oil-immersed power equipment.