With limited water resources in semi-arid regions, which receive precipitation below potential evapotranspiration and are characterized by excessive heat and drought stress, drought is one of the most severe abiotic stress which adversely affects crop growth and productivity. This study was carried out to investigate the negative effects of drought stresses on some Egyptian varieties of barley and its alluviation by using Nano silica particle application. To this end, a pot experiment was laid out in a completely randomized design with three replications, this experiment includes three varieties of Egyptian barley (Giza 129, Giza 133 and Giza 136) three levels of drought (80%, 60% and 40% of field capacity) and Nano silica were applied as foliar in concentration of (0.0 , 25.0, 50.0 and 100.0 mg l-1 . The results showed that by water deficit both No of tiller/ plant and plant height (cm), photosynthesis, straw and grains yield and thousand grains weight was significantly reduced in all studied barley varieties, for example, at (40% FC) the reduction in straw and grain yield reached to 39.4, 21.3% for Giza 136 and 31.8, 33.0% for Giza 133 and 11.4, 12.3% in Giza 129 compared to the normal condition (80% FC) respectively. Data revealed the better performance of ‘Giza 129' variety above ‘Giza 133', followed by ‘Giza 136' in the reduction rate of straw and grain yield and photosynthetic features against soil water deficit. On the other hand, Data showed increases have exceeded by 16.9% and 20.6 % in straw and grains respectively at using the highest concentration (100 mg/l) of Nano silica application compared to untreated plant, therefore it could be stated that this concentration of Nano-silica had the ability to mitigate some the adverse effect of drought