Abstract: Miankaleh Biosphere Reserve is located in north of Iran, it covers an area about 68800 ha. In this survey the plant specimens were collected from different parts of area during two growing seasons. The aim of this research was identify the plant species, introducing the Flora and determination of life forms. In Miankaleh area 261 species recognized, that belong to 60 families and 177 genera. Among these families represented in area Asteracea, Poaceae, Papilionaceae, Cyperaceae and Brassicaeae had the highest number of species 34, 34, 26, 10 and 10, respectively. Fifty four species (20.68%) were endemics of Irano-Turanian region, the following species of them were endemics for Iran: Lindelofia kandavanensis, Papaver tenuifolium, P. chelidonifolium, Scorzonera tortusissima, Scrophularia gaubae, Crepis gaubae and Crepis papposissima. Therophytes and hemicryptophytes with 137 species (52.5%) and 76 species (29%) were respectively the most frequent life forms of the Biosphere Reserve.