Abstract: With the seeding-watermelon seeds as raw material, petroleum ether as extraction agent, the ultrasonicassisted extraction technology was used to extract seeding-watermelon seed oil.The influences of particle size, solid-liquid ratio, ultrasonic frequency, ultrasonic temperature and time on the extraction rate and linoleic acid content of seeding-watermelon seeds oil were studied.Through the orthogonal test, the optimal extraction conditions were as follows:particle size 60 mesh, solid liquid ratio 1:8g/mL, ultrasonic frequency 36kHz, ultrasonic temperature 50℃, ultrasonic time 40min.Under these conditions the seeding-watermelon seeds oil extraction rate reached 23.89%.Gas chromatographic (GC) analysis was employed to analyze the components of fatty acid of seeding-watermelon seeds oil which contained:palmitic acid, elaidic acid, oleic acid, linoleic acid.Among them the linoleic acid content is up to 184.37mg/g the highest of all.