The western half of Chaharmahal and Bakhtiari province (Miankouh part of Ardal county) has suitable environmental conditions for the formation of ancient settlements., deep suevey and small mountain plains and its location on the migration route of nomads. 12 Achaemenid sites were identified and recorded during the three survey seasons that were carried out in this area from 2008 until 2011. This article aims to investigate and study the environmental factors and their role in shaping the space of human habitats in the Achaemenid period of MianKouh. And it examines the question of what effect environmental factors have on the formation of Achaemenid period settlements in the Miankouh region of the city? In order to investigate and evaluate the effect of environmental factors on achaemenid , they were analyzed according to factors such as height above sea level, slope direction, distance from the river, land use, slope percentage, geological structure and distance from existing communication routes in the region. We evaluated using percentage statistical methods. The study showed that the natural factors affecting human settlements and then the ancient settlements in the region are water sources, distance and proximity to communication routes, which will be discussed. Also, based on this research, it was found that different natural factors played a different role in the distribution of ancient sites and not all of them follow the same rule. Finally, after analyzing the spatial distribution of the enclosures, two factors: distance and proximity to water sources and communication routes were identified as the most important and effective environmental factors in the formation of inductions of the Achaemenid period in the Miankouh region of Ardel city.