In the most of cases,oil concentrated in the area near oil source, but a part of oil was discovered in the area far away from oil source.How to interpret these reservoirs?What's the difference between these two kind reservoirs in forming characters and key control factors? According to the space collocation and the forming relationship between reservoir (trap) and oil source, the paper classify three different reservoirs distribution types, they are within oil source , in the side of the oil source and outside oil source . Compared to the area within oil source, the area outside oil source had its unique geological conditions and reservoirforming mechanism. Although the reservoirforming condition in area outside oil source was more harshly than in area within oil source, but the area outside oil source could be forming hydrocarbon accumulation in special conditions. The paper researched the geological condition and reservoirforming mechanism in area outside oil source by taking the Chunguang Oilfield of Chepaizi Uplift in west Junggar Basin as an example. It discovered that the key element of reservoirforming outside oil source is abundant oil source sag, favorable cross migration system and profitable matching conditions. As a new prospect territory, the area outside oil source has well prospect potential and space. In the oil and gas exploration, we should pay attention to the possibility of reservoirforming in area outside oil source,and evaluate potential exploration capacity by taking migration conduction as the key research thought.