A set of 72 samples were formalized by mixing pure olive oil with vegetable oils: Corn, Soya bean, Sunflower, cotton by percentages of 5, 10, 20, 30 and 40 percet respectively. Specific extinction at wavelengths 232nm, 266nm, 270nm and 274nm were measured for three replicates of each sample by using Spectroscopy technique in ultra violet range, ΔK value (alterative of variation of the specific extinction at the wavelength of maximum absorption near 270 nm) and R value (EB270nm / EB232nm) were calculated. The results showed the possibility of using ΔK value to detect the adulteration of Olive oil up to 6.5 ±0.004%, 4.4 ±0.004 %, 0.8 ±0.006% and 0.08±0.005% for Soya bean, Corn, Sunflower and cotton oil, respectively. While these values at 270 nm were 5±0.048%, 5.8 ±0.048%, 1.1±0.077% and 2.6±0.053% in the same arrangement. The absorption value at wavelength 232nm did not show any sign in detecting the adulteration. According to R value, the minimum detected percentages of adulteration were 20 and 10 for Corn and Soya been oil, Cotton and Sunflower oil subsequently . We recommend to use ΔK to detect the adulteration of Olive oil mixed with low percentages of vegetable oil.