This research was conducted in the form of three separate experiments with the aim of examining practical solutions to improve the quantity and quality of olive oil. In the first experiment, with the aim of determining the best fruit harvest time, the trend of changes in the quantity and quality of olive oil during four different harvest stages from the beginning of fruit color change every two weeks (12 October, 26 October, 10 November and 24 November) on Four different olive cultivars with oil application (two domestic cultivars Roghani and Zard and two imported cultivars Amphissis and Beladi) were evaluated in 2016. In this part of the study, maturity index, oil content, quality parameters and oil fatty acid profiles were measured. In the second experiment, with the aim of investigating the effect of tree yield on the quantity and quality of oil, growth regulators of benzyl adenine and naphthalene acetic acid each in two concentrations (100 and 150 mg/l) 15 days after full bloom stage were sprayed on four cultivars (Roghani, Zard, Amphissis and Beladi). In this part of the study, the physical properties of the fruit, oil percentage, oil quality indicators, fatty acid profiles and the percentage of initial and final fruit set were measured and studied. In the third experiment, foliar nutrition of zinc in two mineral and chelated forms with different amino acids in two stages of full bloom and 15 days later to evaluate the physical properties of fruit, quantity and quality of oil in different olive cultivars for two consecutive years (2017 and 2018) was performed. In the first year, mineral zinc (zinc sulfate) and chelated with the amino acids histidine, methionine and threonine were applied on Beladi cultivar. In the second year, based on the results of the first year, in addition to the mineral form treatment of zinc, the best aminochelate treatment of the first year (zinc-methionine) was selected and repeated and two treatments of zinc aminochelate zinc lysine and glycine replaced the previous two amino acids. In addition, the amino acid lysine was added. In the second year, the experiment was performed on four cultivars (Roghani, Zard, Amphissis and Beladi). The results of the first experiment showed that in Zard and Beladi cultivars, the highest amount and best quality of oil were obtained on the last harvest date (November 15, equivalent to maturity index of 4.59 and 4.75, respectively). Also, in Amphissis and Roghani cultivars, the most suitable harvest time to extract the highest amount of oil was the fourth harvest stage and to obtain the best quality of oil was the second harvest stage (October 17, respectively, was equivalent to the maturity index of 4.68 and 4.54). Based on the findings of the second experiment, application of both concentrations of BA and NAA improved the physical properties of fruit, quantity and quality of oil in all cultivars compared to the control treatment. BA at a concentration of 150 mg/l was more effective than other functional compounds in improving oil content, fruit physical properties and oil quality factors including chlorophyll content, phenolic compounds and oleic acid content. NAA at a concentration of 150 mg/l was more effective in reducing the initial and final fruit set compared to other applied treatments. Applied growth regulators in this experiment decreased the oxidation index of the oil and increased its resistance to oxidation by increasing the amount of phenolic compounds and oleic acid. The results of the third experiment also showed that due to the application of Zn, the concentration of Zn in leaves and fruits increased significantly compared to the control. So that the concentration of Zn in the leaves increased more than twice due to the application of Zinc sulfate and more than three times due to the application of Zn aminochelates compared to the control treatment. Application of Zn improved the physical properties of the fruits and increased the quantity and quality of olive oil in all studied cultivars. In all factors evaluated in fruit and olive oil, the healing effect of Zn depended on the type of source applied. Aminochelate treatments had a more healing effect than Zinc sulfate treatment. Among the different types of functional aminochelates, Zn-methionine and Zn-glycine were the most effective treatments. With the use of Zn aminochelates, the oxidative stability of the oil increased due to the increase in phenolic compounds, oleic acid content and the ratio of monounsaturated to polyunsaturated fatty acids. Key words: Olive oil, Benzyl adenine, Naphthalene acetic acid, Zinc sulfate, Zinc aminocholate and Oleic acid.