The net primary productivity and potential natural vegetation in the Korean peninsula in the 21st century were estimated by the Miami model and thermal climate, respectively, based on 148 meteorological data sets. In the 21st century, the distribution range of the net primary produtivity in the Korean peninsula was estimated as 1,050 g $DM{cdot}m^{-2}{cdot}yr^{-1}~2,050g;DMcdot m^-2cdot yr^{-1}.; These; values; increased; by; 200g; DMcdot m^{-2}cdot yr^{-1};on;northern;part;and;400g; DMcdot m^{-2}cdot yr^{-1}$ on southern part compared with that of the present century. The potential natural vegetation in the Korean peninsula in the 21st century will change into the followings:coniferous forest on Mt. Paektu area, deciduous broadleaf forest on northern part, and evergreen broadleaf forset on southern part.