Abstract: Fluid Potential is a comprehensive representation of all the underground fluid energy. Different fluids (oil, gas and water) are affected by fluid potential field in different way and shall move according to the respective distribution pattern of the potential field. The structure of fluid systems can be affirmed in a basin through exploring the spatial distribution pattern of underground fluid. As a result, the understanding of oil migration and accumulation may be improved, the favorable accumulating area of oil and gas could be predicated and success ratio of exploration will be enhanced. Since there are not enough drilling wells in the study area,a set of calculating methods for the fluid potential was established on the basis of accessible interval velocity. We applied the method to the case of North Yellow Sea Basin for study of the subsurface fluid(gas) migration.Two types of underground fluid potential field can be distinguished in the Eastern Depression Belt of North Yellow Sea Basin. The high potential field is coincided with the active oil generating depression which is the main source of hydrocarbon generation and dynamic force; and the low potential field is nearly located in the uplifts and slopes. The potential area for petroleum migration and accumulation can be predicted according to the distribution pattern of potential fields.