Improving the efficiency of oil extraction by maintaining the quality and use of new oil resources are key issues to meet the growing need for oils. Accordingly, in this study, the application of ultrasound process as novel method on watermelon seed oil extraction as an agricultural waste was investigated. The physicochemical properties of the oil including refractive index, specific gravity, iodine value, saponification value, acidity and peroxide value, color, fatty acid composition and total phenolic content of the oil were measured and compared with the control sample extracted with solvent alone. Statistical design of response surface with three variables of duration, ultrasonic power and solvent to sample ratio, respectively, in three levels of 30-45-60 min, 100-200-300 W, 1: 5-1: 10-1: 15 w / v was defined, and extraction efficiency and extraction cost were also considered as the response. After optimization, it was found that the best extraction conditions were in 30 minutes, 300 watts and solvent to sample ratio of 15 times volume with 30.5% efficiency and approximate full price of 251673 Rials. compared to the control sample It represented 10%. Among the extraction variables, respectively, solvent to sample ratio and ultrasonic power had the most significant effect on extraction. Watermelon fat, protein, ash and moisture content of watermelon were 24.44%, 17.16%, 2.75% and 4.95%, respectively. By comparing the physicochemical and qualitative properties of the oil, it was found that there was no significant difference between the oils obtained from the ultrasonic process with the control sample, but in terms of total phenolic content index, the oil obtained from this process was 54.7% higher than the control sample. In terms of fatty acids composition of the oil, there was no difference between treatments and the predominant fatty acid of oil was determined as linoleic acid. Physicochemical properties of watermelon seed oil include specific gravity at 20 °C was about 0.92, its refractive index at 25 °C 1.46, iodine value of about 119 mg iodine per 100 g of oil and saponification value at About 211 mg of alkali per gram of oil were determined. comparing the fatty acids composition of watermelon seed oil with grape seed oil was showed that type and amounts of saturated fatty acids of these oils was near and predominant fatty acids of both of theme is linoleic acid and oleic acid that promotes the high quality of watermelon seed oil. Keywords: extraction, Ultrasound, watermelon seed oil, RSM, total phenolic content, yields