The Khan Valley gallery forest with an area of ca.80 ha is situated south of Urmia in west Azerbaijan province, NW Iran. Using transect method, this study examines flora, life form, and chorotypes of the plant species growing in the area. Woody plants were studied within fifty 400 m2 (20 ´ 20 meter) sample plots centered at 0, 20, 50, 100, and 200 m along transects perpendicular to the river axis on both sides at 200 m intervals. Herbaceous plants were examined within 100 m2 (10 ´ 10 meter) sample plots inside the main plots. In this study, 252 species belonging to 43 families and 169 genera were identified, of which Asteraceae, Brassicaceae, Lamiaceae, Fabaceae (Faboidae), Poaceae, and Apiaceae were most abundant in the study area. Our floristic study reveals that the most common plant taxa in the study site are therophytes (38.49%) and hemicryptophytes (37.69%), based on Raunkiaer system, and phytogeographically belong jointly to Irano-Turanian and Euro-Siberian regions.