The experiment was conducted during the two growing seasons of 2013 and 2014 on 13-year old Manzanillo olive trees in sandy loam soil, under drip irrigation system in a private farm located at km 50 of Cairo –Alexandria road in the north west of Egypt. The trees are cultivated at 5×8 m. apart and grown under standard cultural practices. The objective of this study was to evaluate the effect of olive vegetation water (OVW) treated with mixed culture of cyanobacteria strains (Nostocmuscorum, Anabaena oryzae and Spirulina platensis) onManzanillo olive trees under different irrigation levels and to highlight the economic advantages of these practices in improving fruit quality and crop yields. Processes to reduce the toxicity of OVW and make it acceptable for disposal onto soil or into receiving waters were reviewed. The effect of four treatments of different irrigation regime and olive vegetation water(OVW) with Cyanobacteria. Treaments were:a- control: 3400m3/feddan/year(100%)   b.3400m3/feddan/year(100%)+2 liter OVW plus cyanobacteria was diluted in 22 liter of farmwater/tree, C- 2550m3/feddan/year(75%) of the control+2 liter OVW plus cyanobacteria was diluted in 34 liter of farm water/tree, d- 1700m3/feddan/year(50%) of the control +2 liter OVW plus cyanobacteria was diluted in 46 liter of farm water/tree. Data showed that application of irrigation at 100% (irrigated with 2 liter/ tree of OVW plus Cyanobacteria) and diluted in 22 liter of farm water/tree and added in six months  (January up to June) each two weeks gave the highest vegetative growth, flowering characteristics, yield and fruit oil content. Moreover, the same treatment significantly increased N, P, and Mn. This treatment would be recommended under this study and also under similar conditions and which confirmed by the economic study.