The purpose of this study is to provide the basic data necessary for the vegetation management plan of Gahwacheon River area by obtating the distribution and characteristics of the naturalized plants through the flora investigation of the Gahwacheon riverside in the Jinju - Sacheon city. Vascular plants were investigated a total of 538 taxa including 97 families, 306 genera, 487 species, 2 sub-species, 39 varieties, and 10 forms. It accounted for 11.02% of vascular plants(4,881 species) in Korea. Gramineae was the most abundant as 72 taxa(13.4%), followed by Cyperaceae as 61 taxa(11.3%), Leguminosae as 32 taxa(5.9%), Cyperaceae as 25 taxa(5.8%), and Rosaceas as 23 taxa(4.3%). There were surveyed 9 taxa of rare plants such as Aristolochia contorta, Melothria japonica, Phacelurus latif olius, Acorus calamus, Carex capricornis. The endemic plants to Korea were surveyed to be 7 taxa including 6 families, 7 genera, 7 species. The floristic special plants were surveyed to be 51 taxa including 31 families, 46 genera, 47 species, and 4 varieties. Naturalized plant species were 71 taxa including 22 families, 57 genera, 69 species, and 2 varieties, and 4 taxa (5.7%) appeared in Chamaephyte(Ch), 24 taxa groups (33.8%) for annual plants(Th), and 18 classification groups(25.4%) for annual plants (winter type) (Th(w)). It showed the largest percentage. The Hemicrytophyte(H) appeared in 18 taxa (25.4%). As for the phanerophyte, 2 taxa (2.8%) of Megaphanerophyte(MM) and 1 taxa (1.4%) of Nanophanerophyte(N) appeared. Helophyte and Hydrophyte(HH) did not appear. The naturalization rate and the urbanization index were 13.2% and 22.1%, respectively. Ecological disturbance species were 6 taxa including 3 families, 5 genera, 5 species, and 1 varieties. Sicyos angulatus, Ambrosia artemisiifolia var. elatior, Solidago altissima, Paspalum distichum, Paspalum distichum var. indutum may have harmful effects on native plants, these plants must be artificially controlled.