In order to study the lubricating property of low-speed heavy-duty bearing under the condition of different loads and speed, such as the oil film thickness, oil film pressure and changes of oil film velocity. Building model of fluid-structure interaction by using ABAQUS software, and it can get a conclusion: the oil film thickness distributes in rectangular section, the thickness of oil film between the rolling element and inner ring is thinner than that between rolling element and outer ring, the oil film pressure increases gradually at the entrance of the contact zone, and the oil film pressure at the inner raceway contact point is greater than that of the outer raceway. The oil film velocity of the liquid-solid intersection is greater than that of the free surface, and the oil film velocity is the fastest in the contact zone. With the increase of rotating speed, the oil film thickness and oil film pressure increase; with the increase of load, the oil film thickness decreases, and the oil film pressure increases.