Treatment of drought stress has significant increased leaf rolling score, relative water leaf ratio, but decreased plant height and herbage mass on Guinea and Napier grasses. Furthermore, leaf dying score, drought tolerance and tiller number have not effect by drought stress. Water use efficiency of Guinea grass decrease in three times drought stress (DS258), while on Napier grass WUE have same effect with control. According decline of water use efficiency and herbage mass yield of two grasses, Napier was more tolerance to drought stress than Guinea grass.