Abstract: Oil and gas accumulation pattern is of significance for rolling development of an oil field. Through the detailed study of the source, reservoir and cap combination, oil and gas drainage system and migration pattern, we established the oil/gas reservoir pattern for the Dong Ying formation of the JZ-X oilfield. Research results about oil and gas distribution, fluid property variation, reservoir pressure changes and boundary fault activities were presented in the paper. Our results suggest that the migration of oil and gas in the oilfield be caused by differentiation of oil and gas, when hydrocarbon accumulated vertically along the fault in different periods. The migration was characterized by single direction, double oil sources and independent lateral migration along faults. Some new gas reservoirs which are located under the major oil reservoir were discovered and the hydrocarbon reserves in place increased under the guidance of the oil-gas migration pattern. The discovery of gas reservoirs has satisfied the needs of power plants of the field,in addition to the needs as gas source for the surrounding gas fields. The new oil reserves are rather profitable to the oil field.