In this research, total phenolic content, total flavonoids content and total antioxidant activity of defatted sunflower seeds were evaluated. The antioxidant activity was determined using scavenging capacity of diphenyl-1-picrylhydrazyl. The results showed that the extraction of phenolic compounds, flavonoids and free radical-gathering capacity depends on the type of solvent, temperature, and time of extraction. So that the content of the total phenol content, and antioxidant activity (152.026 mg/g and 97.760 %) of the extract of the seeds were higher at the same conditions (80 , 2h) by methanol, and total flavonoid content (21.5 mg/g) was reported to be higher using acetone as the solvent. According to the obtained results, there was found a linear relationship between the percentage of phenolic compounds and radical scavenging activity and an inverse relationship was observed between the level of flavonoids compounds and total phenol content. The results showed that extraction by methanol at 80 and for 2 hours, resulted in higher amounts of phenolic compounds, therefore; the mentioned extract was applied as the natural antioxidants for comparison with synthetic antioxidants (BHA) in sunflower oil. The results revealed powerful effects of extracted sunflower extracts, in which the samples containing 0.1% of extract, acted similar to 0.01% BHA.