This study is to modify the EUTRO5(sub-model of WASP5) for applying river water quality simulation. Because previous version of EUTRO5 has unique kinetic constant for all segment on each constituent, EUTRO5 is not adequate for some river simulation. As this version have each kinetic constant for all segment on each constituent, it will be suitable for model application with rapid changing geometry and kinetic purification of upstream river.