Background and Objectives: According to recent research, olive leaf (OL) has demonstrated significant properties, including antibacterial, antiviral, anticancer, gastro protective and cardio protective properties. The aim of this study was to investigate the chemical composition, and fatty acid composition (FAC) of OL of Marry variety cultivated in Jiroft province of Iran. This study also attempts to identify and quantify the polyphenolic compounds of OL of Mari. Materials and Methods: The content of dry matter (DM), crude protein (CP), ash, fat ether extract (FEE), acid detergent fiber (ADF) and neutral detergent fiber (NDF) of OL, FAC, type and amount of polyphenol compounds, antioxidant activity (AA%), total phenol, tannin, flavonoid contents (TPC, TTC, and TFC, respectively), were determined, all procedures were performed according to the reference methods. Results: The content of DM, and CP, Ash, FEE, ADF, and NDF of OL obtained 94. 7± 0. 08 (%), and 13. 08± 0. 06, 6± 0. 7, 3. 9± 0. 28, 32. 48± 0. 56, 40. 6± 0. 26 (DM%), respectively. The amounts of TPC, TTC and TFC of OL were obtained 108. 24± 0. 09, 56. 85± 0. 10 (mg Gallic acid (GAE)/g dried OL) and 189. 28± . 012 (mg Quercetin (QE)/g dried OL), respectively. Results showed that OLEUROPEIN was the dominant polyphenol (8306. 9μ g/ g of dried OL). The AA% of OL extract was obtained 61%± 0. 9%. The FAC of OL was determined by gas chromatography (GC) and the results showed linoleic acid (27. 2± 0. 33%) followed by oleic acid (21. 8± 0. 40 %) as the most abundant unsaturated FAs found in the OL, respectively. Conclusions: These results demonstrated that OL is a rich source of natural and bioactive compounds, which can be used in the food industry, animal feed, and so on for improving the nutritional value and functionality.