The present survey was conducted to investigate the ecological distribution range of woody species and the most important factors affecting their distribution in the Zagros forests of Ilam province. physical and chemical characteristics of soil, as well as topographical factors, were assessed in 109 circular sampling plots with an area of 500 m2 n four forest areas with an altitude range of 800-2400 m. The vertical distance of the plots on the slope aspect was 100 m, and the distance of the sampling routes varied from 500-1000 m. ecological distribution range index was calculated based on the most important factors affecting species distribution. Based on the Principal Component Analysis (PCA), the most significant factors include: the percentage of theclay, Potassium, nitrogen, carbon, sand, phosphorus, and altitude. species such as Amygdalus orientalis, Lonicera nummularifolia, Daphne mucronata and Cerasus mahaleb and Acer monspessulsnum were found at hight altitudes with the highest levels of carbon, nitrogen, potassium and phosphorus. In addition, Quercus brantii along with Acer monspessulanum and Daphne mucronata showed the highest ecological distribution range while Pistacia atlantica, Amygdalus arabica and Amygdalus orientalis species respectively has the lowest values. Overal, results indicate that topography and soil factors play an important role in the distribution of woody species in the studied areas.