Field experiment was conducted and located at desert road . Adult and similar olive trees,10 years old during the two growing seasons of 2014 and 2015. Two olive cultivars,  Manzanello and Maraki  were selected to investigate the effect of irrigation regimes sue has 100% ( 4384 m³/feddan ), 85% ( 3892 m³/feddan) and 70 % (3398 m³/feddan ) which applied after full bloom stage started first of May in both growing seasons–one of most sensitive stage of olive trees –as well as the effect of rice straw mulching treatments. Water scarcity problem is globally getting worse. The vast of majority of annual water supply in Egypt is used for irrigation. So, water saving and conservation is essential object to support agricultural sector especially in the new reclaimed land. The experiment was designed in a split– split plot with three replicates. Data revealed that using 70 % irrigation regimes combined with mulching treatment enhanced vegetative growth characteristics, i.e., shoot length, number of leaves/shoot, leaf area as well as flowering characteristics, i.e., as number of flowers per inflorescence, perfect flowers, sex ratio, number of male flowers, number of female flowers, and flowering density and fruit yield. Minerals as N, P and K in olive leaves were the highest by 70% level combined with rice straw mulching 85 % irrigation level enhanced fruit quality as well as fruit oil content for both cultivars. Water use efficiency (WUE) was increased by decreasing amount of applied water. Highest  value of WUE was obtained  by using 70%  irrigation level. Oil content of fruit in Maraki was higher than Manzanillo such differences were due to their heritability. Economic evaluation of net income recommended using 70% of irrigation regime with rice mulching.