Abstract: By analysis of reservoir formation condition,the authors discussed the characteristics of oil pool formation and the condition of petroleum accumulation in the area Fang 3,Songfangtun Oilfield,north of Songliao basin.In this district,there are mainly fault traps and fault-lithology traps.The key control factor of reservoir generation is that the fault is located on the upper side of reservoir incline.The scale of the faults to communicate Putaohua reservoir with source rock is generally greater and that to communicate Fuyang reservoir with source rock is commonly smaller.The source rock is the mud stone of Qing shankou Formation,the advantaged source rock is located in or nearby the research area and there is not almost contribution of source rock in the main body of Sanzhao depression.The porosity and permeability of reservoir and oil migration conditionin Putaohua oil layer are excelled to that Fuyang oil layer.It is thought that the petroleum potential in Putaohua oil layer is better than that in Fuyang oil layer by in tegrated analysis.