Abstarct: Organic geochemistry has a scientific distribution in exploration of hydrocarbon Reservoirs. For this reason, today there is no drilling in advance of organic geochemical survey. The use of more than one organic Geochemistry technique is usually recommended. Nosrat oil field is the study area for this research, which is situated in the Persian Gulf near the marine boundary of Iran and the United Arabic Emirates (Fateh field), 35 kilometers south-east of the Sirri island. The main propose of this research is to evaluate the Nostat source rocks. In this study, the results of Rock-Evall pyrolysis and gas chromatography were used. The Rock-Evall pyrolysis analysis was done on 107 cutting (59 sample from Pabdeh Formation, 33 samples from Gurpi Formation, 6 samples from Ilam Formation, 7 samples from Lafan Formation and 2 samples from Sarvak Formation) of borehole NH01. Pabdeh, Gurpi, Ilam and Lafan Formations are no polluted, but Sarvak Formation is non-indigenous. The kerogen type for these formations is a combination of II-III types. Quality of hydrocarbon Pabdeh Formation is lean-good, fari–good for Gurpi and Ilam, Lafan and Sarvak are poor. Sarvak and Lafan Formations could not be considered as source rock. Pabdeh and Gurpi Formations are in the beginning of oil window and Ilam, Lafan and Sarvak are immature. In detail investigation, firstly bitumen from 8 samples (3 samples from Pabdeh (Pb#1, Pb#2, Pb#3), 3 form Gurpi (Gu#1, Gu#2, Gu#3), 1 from Ilam (Il) and 1 from the Sarvak formation(Sv)) was extracted and used for the column chromatography and then the saturated part has been sent for gas chromatography. Sample Pb#3 there was no biodegradation, and deposited in the reduction and marine Environment. Samples Pb#1,Pb#2, Gu and Sv there were no on biodegradation, deposited in the reduction and marine environment with the input little of Terrestrial. Sample Il has affected biodegradation, deposited in the oxidizing and Terrestrial Environment. Sample Gu#2 was no biodegradation, deposited in the oxidizing and terrestrial environment. The column chromatography for the 8 samples was considered a paraffinic composition with the exception for Pb#3, as naphthenic. According to the low terrigenous/aquatic ratios (Tars<1) for the samples, marine environment in the source rocks was confirmed. According to the vertical drainage system of the oil field, Pabdeh Formation classified as medium potential source rock, Sarvak Formation has the lowest potential. Exclusive of the Pabdeh Formation, all the other formations (Gurpi, Ilam, Lafan and Sarvak) are an indicator of low potential source rock and Pabdeh formation is an indicator of middle potential source rock. All the above results were confirmed by the geochemical logs. Keywords