Water stress “an abiotic stress" is one of the main challenges which constrain olive cultivation in reclaimed area in Egypt. It can impair the growth and production performance of olives. Many investigations recommended spraying dolomite nano-particles "Lithovit^® fertilizer" to reduce the effect of water stress. We believe that we have designed an innovative solution to follow up the effect of spraying dolomite nano-particles (Ca CO₃ & Mg CO₃) on olive trees which exposure to different irrigation levels. Four concentrations of dolomite nano-particles were sprayed on olive (Olea europaea var. Picual) trees (0, 2, 4 and 6 g/L) under three irrigation levels (50, 75 and 100% of evapotranspiration for crop “ETc") during 2017, 2018 seasons. Strong evidence of irrigation at 75% of ETc was found on olive growth, flowering and fruit setting. It was the best irrigation level to balance between vegetative growth and blooming. Moreover, there were significant variations between spraying dolomite nano-particles at 2 g/L and other concentrations on flowering and fruit setting. Furthermore, the interaction between spraying dolomite nano-particles and irrigation levels cleared that spraying dolomite nano-particles at 2 g/L and irrigation at 75% of ETc enhanced flowering and fruit setting.