BACKGROUND: Oxidation of lipids results in changes that may affect the nutritional quality, wholesomeness, colour, flavour and texture of food. Canola oil is prone to oxidation because of high unsaturated fatty acids. Using synthetic antioxidant due to the possibility of toxic and carcinogenic effects is limited. Thus, it is important to research on replacing synthetic antioxidants by natural antioxidant. Objectives: The aim of this research was identification of the chemical compounds of Carum copticum essential oils (CEOs) and investigation of antioxidant and antiradical properties by using Diphenylpicrylhydrazyl (DPPH) method and β-carotene/linoleic acid system and assaying its antioxidant capacity in canola oil. Methods: Carum copticum essential oil was analyzed by GC/MS. Anti-radical activity of (CEOs) was investigated by using various methods and then antioxidant  was tested by measuring the peroxide value and thiobarbituric acid of canola oil samples containing different concentrations of C. copticum essential oil and synthetic antioxidant(BHT). Results: Results showed that thymol (36.4%), γ-terpinene (21.73%) and ρ-cymene (31.3%) were the major compositions of essential oil. IC50 value of (CEOs) was 21± 0.2  µg/ml. In both systems, the sequence of the power of antioxidant activity was BHT then C. copticum essential oil. In addition, by increasing the concentrations, their antioxidant activities were increased. Statistical results revealed C. Copticum essential oil at concentration of 400 ppm (P>0.05). Conclusions: Carum copticum essential oil is a potent antioxidant for stabilization of canola oil and can be used as a natural antioxidant. It seems that after complementary test it can be used as natural antioxidant in foodstuff, especially in edible oils.