This study aims to investigate the flora of Mt. Cheonma (Namyangju-si, Gyeonggi-do, Korea), including Korean endemic, rare and endangered plants. To support the biodiversity and usefulness of this investigation, we checked the red list plants, floristic regional indicator plants, climate change adaptation target plants and naturalized plants, and compared composition of plant species in Mt. Cheonma with nearby mountains. Totally, we performed 22 field investigations from April 2012 to October 2014. The number of vascular plants in this region is 433 taxa and comprised of 94 families, 266 genera, 378 species, 2 subspecies, 46 varieties, and 7 forms. Among them, there are 13 endemic plants designated by Korean Forest Service, whereas only 10 taxa are endemic species by Korean Ministry of Environment (KME). According to the IUCN criteria, there are 12 rare and endangered plants composed of 9 Least Concerned (LC), 2 Vulnerable species (VU), and one Endangered species (EN) found by Korea National Arboretum (KNA). Meanwhile, 8 taxa including 7 Least Concerned (LC) were found in Red List of KME. The floristic regional indicator plants designated by KME were 49 taxa. In addition, there are 14 taxa in The Adaptable to Climate Change Plant List designated by KNA, while only 19 taxa are naturalized plants. Generally, there are 190 common taxa in Gwangju Mountains area, and only 51 taxa are distributed in Mt. Cheonma.