Abstract: Wuerxun Sag is an important oil-bearing area in the south of Hailaer basin, which has great exploration potential. This paper determines the main source rocks in Wuerxun Sag by oil source correlation, analyzes the development characteristics of source rocks in different regions and geochemical indicators such as organic matter abundance and type, evaluates the oil generation maturity and accumulation stage of main source rocks in Wuerxun Sag, and judges the oil and gas filling history and predicts the preferred exploration potential position by measuring the homogenization temperature of fluid inclusions. It is found that the oil source in different areas of Wuerxun Sag is not identical. The oil reservoir in the north of Wuerxun Sag is derived from the parent material of mud shale rock of Nantun formation. In the south of Wuerxun Sag, besides the mud shale of Nantun formation, there is oil flow from dark mudstone of Tongbomiao formation. Wuerxun Sag has two stages of hydrocarbon accumulation: The first stage is from the later Yimin formation to the early Qingyuangang formation; The second stage is the late structural activity of Qingyuangang formation, which makes the early oil reservoir redistribute and inject new traps. It is considered that the west side of Wubei sag and the east side of Wunan sag are two important exploration potential zones.