The present study focuses on facies analysis and the reservoir characteristics of the Asmari Formation in the Aghajari oilfield (located in the Zagros fold-thrust belt, southwest Iran), and how they are linked to depositional environments and reservoir characteristics. This formation consists of about 380 m carbonates with some siliciclastic intercalations. Based on the integration of 1200 m of core description and petrographic analyses of 2500 thin sections, 9 carbonate and 1 evaporite microfacies along with 2 siliciclastic petrofacies were identified. Facies analysis shows that the Asmari Formation sediments were deposited in a homoclinal carbonate ramp within open marine (facies association A), shoal (facies association B), restricted lagoon (facies association C), tidal flat (facies association D), and beach (petrofacies E) environments. Macroscopic and microscopic studies reveal that the main porosity types include interparticle, growth framework, vuggy, intercrystaline, moldic and fracture. Based on Routine core analysis (RCA), porosity of the studied reservoir varies from 0.001 to 25.8%, with an average of 12.5%. The permeability ranges from zero to 1514 mD with an average of 94.27 mD. There is a good relationship between trend of mercury injection capillary pressures (MICP) and depositional environment. Therefore, facies deposited