This study was performed to investigate the flora of Gangneung-si (Kangwon-do). The collected vascular plants were composed of all 903 taxa including cultivated species, and classified into 755 species, 1 subspecies, 124 varieties, and 23 forms of 450 genera under 126 families. Among the investigated vascular plants, 16 taxa were Korean endemic species. Law-protected plants by Ministry of Environment were 2 taxa. The special plants based on floral region by Ministry of Environment (2006) were 75 taxa; V rank species 2 taxa, IV rank species 9 taxa, III rank species 21 taxa, II rank species 14 taxa, and I rank species 29 taxa. A naturalized plants were 45 species, correspond to 15.5% of totaling 290 species appeared in South Korea. Floristic geography of the investigated area was regarded as the boundary between middle regions in floristic pattern of the Korean peninsula.