Abstract: A total of 45 crude oil samples collected from Tarim, Beibuwan, Junggar, Qiongdongnan and Jianghan Basins were analyzed by comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry (GC×GC-TOFMS). Standard samples were used for qualitative and quantitative analysis of eighteen C₁₀ compounds in crude oil, including six monoterpenoid hydrocarbons, i.e., 2, 6-dimethyloctane (2, 6-DMO), 2-methyl-3-ethylheptane (2-M-3-EH), 1, 1, 2, 3-tetramethyl cyclohexane, t-1-methyl-4-isopropylcyclohexane, 1-methyl-3-isopropylbenzene and 1-methyl-4-isopropylbenzene.The results show that there are six monoterpenoids with different abundances in crude oil samples. Abundant monoterpenoid hydrocarbons were detected out in catalytic hydrogenation products of higher plant essential oil, suggesting terrestrial higher plant is a possible source of monoterpenoid hydrocarbon. The assemblage of new molecular marker parameter 2-M-3-EH/2, 6-DMO(MTR) and pristine/phytane (Pr/Ph) can be used to effectively distinguish crude oil samples derived from source rocks under different sedimentary environments. The crude oil from source rocks under reducing sedimentary environment has higher MTR and lower Pr/Ph values, whereas the crude oil derived from source rocks under oxidative sedimentary environments possesses lower MTR and higher Pr/Ph values. The quantitative data prove that the differences in MTR and Pr/Ph values are due to the variations in 2-M-3-EH and Ph contents of crude oil, i.e., for two kinds of crude oil, the content ranges of 2, 6-DMO and Pristane are very similar, while those of 2-M-3-EH and Phytane are quite different. The contents of 2-M-3-EH and Phytane are higher for crude oil derived from source rocks under reducing sedimentary environment, while lower for crude oil derived from source rocks under oxidative sedimentary environment. Both MTR and Pr/Ph can be used to identify the redox degree of sedimentary environment for source rocks, which is of great significance to light oil and condensate oil with very low or insufficient bio-marker content.