Abstract: The content of diamondoids in crude oil from the hinterland of Junggar Basin was analyzed by GC, MS and GC-MS methods. The applicability of diamondoid indices to identify and evaluate oil maturity was discussed. The diamondoid content in crude oil is (200-500)×10^-6. The concentration index of diamondoids can classify oil types effectively, and the adamantane isomerization index can be used to evaluate oil maturity. The oil in the hinterland of Junggar Basin can be divided into two types. Type I oils were generated early with relatively lower maturity and lower content of diamondoids. The content of adamantane is relatively higher. The concentration index A/1-MA ratio is distributed in the range of 0.50-0.71, and the maturity index MAI value is smaller, between 0.41 and 0.50, which is far away from the hydrocarbon source depression. Type Ⅱ oils were generated late with relatively higher maturity and higher content of diamondoids. The content of 1-methyladamantane is higher. The ratio of A/1-MA is in the range of 0.30-0.37, and the MAI value is between 0.52 and 0.69, which fall within the hydrocarbon source depression. The distribution pattern is consistent with the direction of oil migration. That is, the late filling oil displaced the early filling oil away from the hydrocarbon generation depression, which proves that the oil in the hinterland area migrated from the area of the well Pen 1 sag to the north.