The research on road-region boundary based on vegetation index is of great significance for road construction decision and eco-environmental protection. Taking Landsat 8 OLI remote sensing image of Guangkun highway as a case, the law of vegetation growth in different buffer zones was discussed based on vegetation index, so as to provide a criteria for determining road-region boundary. The results showed that NDVI, ARVI and IAVI vegetation indices can be used for monitoring road ecological changes constantly. The influence of road on adjacent vegetation will decrease with the increase of distance. The influence is strong within 200 m, and tends to be stable around 600 m. Moreover, road-region boundary can be scaled dynamically in which road-region boundary should be relaxed to the minor influence area or the non-influence area in route selection or reduced to the main affected area in ecoenvironmental assessment.