Abstract: This paper presents the varied characteristics of biomarkers of saturated hydrocarbon and aromatic hydrocarbon in process of deep thermal fluid. Under the impact of thermal energy of deep fluid, the values of m($\sum{n}C_{21-}$)/m($\sum{n}{C_{22}}^{+}$) and m(Pr)/m(Ph) increase while the n-alkane's odd-even carbon number predominance gets weaken; the values of m(C₃₁ hopane)/m(C₃₀ hopane) and m(C₃₅ hopane)/m(G₃₄ hopane) decrease, while those of m(C₂₇-C₂₉ sterane 20S)/m[C₂₇-C₂₉ sterane (20S+20R)] and m(C₂₇-C₂₉ steran ββ)/m[C₂₇-C₂₉ steran (ββ+αα)] increase, aromatic hydrocarbons are enriched. If the deep thermal fluid is rich in hydrogen, the biomarkers like m($\sum{n}C_{21-}$)/m($\sum{n}{C_{22}}^{+}$),m(Pr)/m(Ph), m(Ts)m(Ts+Tm), etc. will fail in indicating matunity and sedimentary environment. Based on these, the identified biomarkers of organic matter in crude oil or hydrocarbon source rock that influenced by the deep thermal fluid are proposed preliminarily in this paper.

Key words: thermal fluid, biomarker, saturated hydrocarbon, aromatic hydrocarbon