According to the comparison of biomarker features of n-alkanes and steranes in source rocks of Chang 7, Chang 9 and Chang 10 and crude oil of Chang 8, Chang 9 and Chang 10 in the middle-western Ordos Basin, in this paper oil-source correlation is revealed. Biomarker features of n-alkanes and steranes in source rocks and crude oil are different in the Lower Yanchang Formation of different areas. Crude oil of within Chang Chang 8 originated from the source rocks 7 in the western area, and it came from the source rocks within Chang 7 and Chang 9 in the eastern and southern area; crude oil of Chang 9 originated from the source rocks within Chang 10 in the western area, and it came from the source rocks within Chang 9 and Chang 10 in the eastern and southern area; crude oil of Chang 10 originated from the source rocks within Chang 10 and Chang 9 in the southern area.