This examination was conducted during the 2018 and 2019 seasons to examine the effect of foliar application of (0.5 to 2 %) Spirulina Platensis Algae and (50 to 150 ppm) salicylic acid on Flowering (%), growth, yield, and fruit quality of Koroneiki olive trees grown under the sandy soil. The trees received two sprays at the mid of December and the 1st week of Jan. Applications of Spirulina Platensis Algae at 0.5 to 2 % and salicylic acid at 50 to 150 ppm alone, or combination had a pronounced stimulation on vegetative growth, shoot length, leaf area and the number of leaves, percentage of N, P and K in leaves, Flowering (%), yield, fruit weight and dimensions and fruit oils % over the control. The stimulation of these parameters was materially associated with increasing concentrations of both materials. Using Spirulina Platensis Algae was superior to using salicylic acid in this regard. Combination applications were practical than using each material alone in this respect. Application of two sprays at mid-December and the 1st week of Jan. of a mixture of 1 % Spirulina Platensis Algae and 100 ppm salicylic acid gave the best yield and fruit quality results Koroneiki olive trees grown under the sandy soil.