The Shahbazan Formation was deposited in the foreland basin in southwestern Iran (Lorestan Ba- sin)． In this research，microbiostratigraphy and depositional environmental implications related to the Shahba- zan Formation at the northern flank of Chenaerh anticline are discussed． Carbonate sequences of the Shahbazan Formation consist mainly of large benthic foraminifera along with other skeletal and non- skeletal components． Two biozones have been recognized by distribution of large foraminifera in the studied area that indicate middle Eocene age (Lutetian)． Based on analysis of large benthic foraminiferal assemblages and microfacies features， 7 different microfacies have been recognized，which can be grouped into three depositional environments: in- ner，middle and outer ramps．