The important species of eucalyptus are Eucalyptus microtheca and Eucalyptus sargentii. The species use for forestry and plantation for create green space with a relatively long history. The aim of this experiment determining water requirements, Kc and water use efficiency of this species whit drainage and weighting lysimeters and three old trees in Yazd Shahid Sadughi Desert Research Station. The experiment carried out whit three treatments, 100?% (control), 70% (moderate stress) and 40% (severe stress) field capacity in a completely randomized design with three replications. The results showed that E.microtheca and E.sargentii have evapotranspiration annual less than potential evapotranspiration and the species called of drought resistance. The Kc of E.microtheca under field capacity, 0.45 with the annual water requirement of 833.4 mm and E.sargentii, 0.67 with an annual water requirement of 1227.9 mm. Water use efficiency, was also influenced by the amount of water available, so that they have access to water at moderate stress reduction, increased water use efficiency. Although E.microtheca of resistance to drought and has low water requirements, nevertheless, both species could be drought resistant species and are suitable for forestation, creation of green areas and fixation of sand dunes in arid and semi arid zones